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  • 1
    ISSN: 1432-0738
    Keywords: Dichlorvos ; Teratology ; Inhalation ; Rat ; Rabbit ; Dichlorvos ; Teratologie ; Inhalation ; Ratte ; Kaninchen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung An Kaninchen und Ratten wurde die teratogene Wirkung von inhaliertem Dichlorvos untersucht. Im Versuch waren primipare Kaninchenweibchen der Rasse “Dutch” mit einem Anfangsgewicht von 2 bis 3 kg und primipare Rattenweibchen vom Stamm “Carworth Farm E“ mit einem Anfangsgewicht von 200 bis 300 g. Die Tiere wurden während der gesamten Trächtigkeit folgenden Konzentrationen in der Atemluft ausgesetzt: 0,25, 1,25 und 6,25 μg Dichlorvos pro Liter Luft. Ein zusätzliches Experiment am Kaninchen wurde mit 2 und 4 μg Dichlorvos pro Liter Luft durchgeführt. Die Behandlung wirkte weder beim Kaninchen noch bei der Ratte teratogen. Selbst Konzentrationen, die für die Kaninchen tödlich waren, und die eine deutliche Cholinesterasehemmung in Plasma, Erythrocyten und Gehirn der Ratten und Kaninchen hervorriefen, wurden ohne Schädigung für die Feten vertragen.
    Notes: Abstract The teratogenic potential of inhaled dichlorvos vapour for rabbits and rats was investigated on the offspring of primiparous female Dutch rabbits weighing 2 to 3 kg and primiparous female Carworth E strain rats weighing 200 to 300 g. The animals were exposed throughout pregnancy at concentrations of 0.25, 1.25 and 6.25 μg dichlorvos per litre of air. In an additional experiment pregnant rabbits were exposed to concentrations of 2 and 4 μg dichlorvos per litre of air. The results gave no indication that dichlorvos vapour is teratogenic in rabbits or rats even at exposure concentrations resulting in maternal deaths in rabbits, and causing depression of plasma, erythrocyte and brain cholinesterase activities in pregnant animals of both species.
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  • 2
    ISSN: 1432-1106
    Keywords: Ventromedial hypothalamus ; Single units ; Spontaneous and stimulated activity ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The relationship between mean firing rate and activity pattern was studied in 177 neurons in the ventromedial hypothalamus of rats immobilized by Remyolan. Stationary epochs of spontaneous or stimulated activity containing at least 512 interspike intervals were analyzed with the LINC computer. The most frequently encountered interval histograms (IHs) were of the exponential (35%) or gamma 2 (25%) type. The IH shape remained unchanged even if the average firing rate was varied over a wide range (from 20/sec to 2/sec) by polarization through the recording microelectrode (2–5 nA, 1–10 min) or by intracarotid injection of glucose (0.1 ml, 10–25%). The coefficient of variation (CV = SD/ mean interval) was 1.03 for the spontaneous and 0.90 or 0.95 for the activity influenced by polarization or glucose, respectively. Since according to other studies sensory stimulation decreases CV by reorganization of the synaptic input, it is suggested that polarization and glucose affect predominantly the postsynaptic elements without significantly changing the presynaptic activity pattern.
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  • 3
    ISSN: 1432-0533
    Keywords: l-DOPA ; Neoplasm, Striatal ; Motor Behavior ; Rat ; Catecholamines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary After administration ofl-DOPA to a rat with a unilateral striatal neoplasm of the nucleus caudatus-putamen, postural asymmetries and rotating behavior were observed. These observations are discussed in relation to the activity of catecholamines within the central nervous system.
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  • 4
    ISSN: 1432-0568
    Keywords: Rat ; Cold ; Pineal gland ; Synaptic vesicles ; Zinc iodide-osmium tetroxide (ZIO) reaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung In den synaptischen Bläschen der Nervenendigungen der Epiphyse von Ratten, welche 2 und 4 Tage einer Temperatur von −6° bis −8°C ausgesetzt worden waren, hat man eine signifikante Vermehrung des Zinkjodid-Osmiumtetroxyd (ZIO) reaktiven Materials festgestellt. Der durchschnittliche Durchmesser der ZIO-positiven synaptischen Vesiculae betrug bei den Kontrollratten 234 Å und bei den Ratten, welche 2 und 4 Tage unter der Kälte gelebt hatten, 380 Å, bzw. 379 Å. Die ZIO-Reaktion war bei den Kontrollratten in 49,3% der synaptischen Vesiculae positiv, nach zweitägiger Kälteeinwirkung waren 58,7% und nach viertägiger Kälteeinwirkung 72,1% der synaptischen Vesiculae ZIO-positiv. Auf Grund der vorliegenden Arbeit war es jedoch nicht möglich zu entscheiden, ob die Vermehrung des ZIO-reaktiven Materials mit einer gleichzeitigen Zunahme der biogenen Amine verbunden ist.
    Notes: Summary In the synaptic vesicles of pineal nerve endings of Wistar rats exposed for 2 and 4 days to a temperature of −6° to −8° C, a significant increase of the zinc iodide-osmium tetroxide (ZIO) reactive material was observed. The mean diameter of ZIO reactive synaptic vesicles of control rats was 234 Å; in rats exposed to cold for 2 and 4 days it was 380 Å, respectively 379 Å. In control rats the ZIO reaction was positive in 49,3% of the synaptic vesicles. The reactivity increased to 58,7% in rats exposed to cold for 2 days, and to 72,1% in rats exposed to cold for 4 days. However, the results of the present study do not permit to conclude if an increase of ZIO reactive material is accompanied by a simultaneuos increase of biogenic amines.
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  • 5
    ISSN: 1432-0568
    Keywords: Cerebellum ; Neurogenesis ; Autoradiography ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Time of origin of various neuronal elements in the cerebellum of rat was established with the aid of tritiated-thymidine-autoradiography. The earliest nerve cells to form were the Purkinje cells, and they came into existence on days 15 and 16 of gestation. Interstitial nerve cells had their genesis on days 15, 16, 17 and 18, and the marginal cells on day 16 of the embryonic development. The Golgi cells were found to come into existence on days 17, 18 and 19 of gestation. On day 21 of gestation a number of small-medium-sized nerve cells, which were smaller than the Golgi cells but larger than the granule cells, were seen to come into existence. Finally, the earliest stock of granule, basket and stellate cells, primarily in the nodulus, flocculus and para-flocculus, were observed to have been formed on the day 21 of embryogenesis.
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  • 6
    ISSN: 1432-0568
    Keywords: Corticotropin-Releasing Factor ; Median eminence ; Rat ; Histology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung In der Zona externa infundibuli der normalen Ratte kommen geringe Mengen „Gomori-positiver” Granula vor. Nach bilateraler Adrenalektomie erfolgt eine Vermehrung der Granula, die sich durch Gabe von Hydrocortison einschränken oder verhindern läßt. Dieser Befund hat zu der Annahme geführt, daß die Granula das morphologische Äquivalent des Corticotropin-releasing factor (CRF) darstellen. Morphometrische Untersuchungen an 160 weiblichen Wistarratten zeigen, daß die Menge der nach bilateraler Adrenalektomie in der Zona externa infundibuli nachweisbaren „Gomori-positive” Granula von der postoperative Überlebensdauer abhängt. Die Granulamenge nimmt zunächst bis zum 14. Tag p.o. zu und fällt dann wieder ab. Substitution bilateral adrenalektomierter Ratten mit Hydrocortisonacetat-Kristallsuspension bewirkt eine dosisabhängige Verminderung der Granulamenge, wenn die Behandlung am Operationstag begonnen wird. Applikation von Hydrocortisonacetat-Kristallsuspension vom 14.–21. Tag p.o. führt dagegen zu einer gesteigerten Granulavermehrung. Auch bei stärkster Vermehrung sind die Granula stets nur im Infundibulum und nicht in anderen Bereichen des Hypothalamus nachweisbar. Sie besitzen bei bilateral adrenalektomierten Tieren ein charakteristisches Verteilungsmuster mit besonders hohen Konzentrationen in den paramedianen Abschnitten des rostralen Infundibulumdrittels. Aus der Art und Weise ihrer Verteilung ist zu vermuten, daß die Granula 2 Nervenfaserzügen angehören und ein Neurosekret darstellen. Nach den vorliegenden Untersuchungen besteht zwischen dem Verhalten der „Gomori-positiven” Granula in der Zona externa infundibuli und dem aus pharmakologischen Untersuchungen bekannten Verhalten des Corticotropin-releasing factor eine weitgehende Parallelität. Sie legt nahe, die Menge der Granula als Parameter der CRF-Aktivität zu verwenden.
    Notes: Summary In the zona externa infundibuli (outer layer of the median eminence) of the normal rat a minute number of “Gomori-positive” granules can be detected. Following bilateral adrenalectomy their number increases. This augmentation can be restricted or inhibited by administration of hydrocortisone, a finding, which has led to the assumption that the granules are the morphological equivalent of the corticotropin-releasing factor (CRF). Morphometrical studies on 160 female Wistar rats show that following bilateral adrenalectomy the quantity of “Gomori-positive” granules is dependent on the length of the post-operative survival period. Up to the 14th day p.o. the quantity of granules increases; from then on it diminishes. Substitution of bilaterally adrenalectomized rats with hydrocortisone acetate crystal suspension results in a dose-dependent decrease in the quantity of granules if treatment is begun on the day of operation. In contrast, administration of hydrocortisone acetate crystal suspension from the 14th to the 21st day p.o. results in increased augmentation of the granules. Even when maximum augmentation of the granules is reached, they are invariably found only in the infundibulum and not in other regions of the hypothalamus. In animals that have been subjected to bilateral adrenalectomy, the granules show a characteristic pattern of distribution, with particularly high concentrations in the paramedian parts of the rostral third of the infundibulum. The manner in which the granules are distributed suggests that they are a neurosecretory substance localized in two fibre tracts. The present study points to a close parallelism between the behaviour of the “Gomori-positive” granules in the zona externa infundibuli and that of the corticotropin-releasing factor as revealed by pharmacological investigations. It would seem that the quantity of granules can be used as a parameter of CRF activity.
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  • 7
    ISSN: 1432-0568
    Keywords: Monoamines ; Brain ; Ontogeny ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The early ontogeny of the monoamine neuron systems in the rat brain has been analysed using Falck-Hillarp fluorescence histochemistry. Serial sagittal sections of embryos with a crown rump length between 7 and 13 mm, approximately corresponding to gestational days 12 to 15 were obtained from mothers treated with a monoamine oxidase inhibitor given in order to increase the monoamine levels of the embryos. 5-hydroxytryptamine (5-HT)-neurons made their first appearance in the 8 mm embryo, dopamine (DA)-neurons in the 9 mm embryo, and noradrenaline (NA)-neurons in the 11 mm embryo. Small, rounded, weakly fluorescent cell bodies forming sparse aggregations appeared first. Fluorescent processes of two types soon appeared. Short processes from the cell bodies were running perpendicular to the long axis of the brain stem within the cell groups, while long slender axon bundles could be traced ascending through the met- and mesencephalon and into the prosencephalon as well as descending in the myelencephalon andspinal cord. In the 12 mm embryo the primordial DA cell formation of the substantia nigra with its striatal projections, the 5-HT neuron formations of the caudal mesencephalon, met- and myelencephalon as well as the NA neurons of the met- and myelencephalon are relatively well developed. It is concluded that the monoamine-neurons develop mechanisms for synthesis and storage of amines at a very early stage during ontogeny, thus recapitulating the phylogeny of these old systems. Likewise, monoamine oxidase is present early. The presence of neurotransmitters specifying the different developing neurons long before development of their nerve terminal areas and therefore before the establishment of normal synaptic function may indicate a role of these substances during ontogeny other than transmission of nerve impulses.
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  • 8
    ISSN: 1432-0533
    Keywords: Experimental CNS Tumours ; N-Nitrosomethylurea ; Ethylnitrosourea ; Cell Culture ; Clonal Growth ; Aggregation Pattern ; Transplantation ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Two sarcomas, one neurosarcoma and one polymorphous tumour of uncertain classification of the central nervous system of the rat induced by N-nitrosomethylurea or ethylnitrosourea were the source of 14 clones. The cytomorphology and the aggregation pattern of the clonesin vitro are described. The malignancy and histology were checked by homologous transplantation. All the clones formed sarcoma-like structuresin vivo, but it was difficult to decide whether these neoplasias were real sarcomas or very dedifferentiated glial tumours. The differences in cytology observedin vitro were greater than the histological differencesin vivo.
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  • 9
    ISSN: 1432-0738
    Keywords: Mouse ; Rat ; Brain ; Light-Dark-Programming ; Circadian ; Toxicity Rhythms ; Acetylcholine ; Pilocarpine ; Oxotremorine ; Carbachol ; Physostigmine ; Neostigmine ; Atropine ; Scopolamine ; Atropine Methyl Nitrate ; Maus ; Ratten ; Gehirn ; Beleuchtungsprogramm ; Circadianer Toxicitätsrhythmus ; Acetylcholin ; Piloearpin ; Oxotremorin ; Carbachol ; Physostigmin ; Neostigmin ; Atropin ; Scopolamin ; Atropin-methylnitrat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Nach Adaptation an ein Licht-Dunkelprogramm (8.00 bis 20.00 Licht, 20.00 bis 8.00 Dunkelheit) wurde der Acetylcholingehalt (ACh) im Mittelhirn und N. caudatus von Ratten sowie im Gesamthirn von Mäusen bestimmt. Die höchsten ACh-Konzentrationen wurden bei Ratten um 24.00 gefunden; die höchsten ACh-Werte bei der Maus waren nicht signifikant von den Konzentrationen um 24.00 und 12.00 verschieden. Signifikante ACh-Minima traten im Mittelhirn der Ratte um 12.00, im N. caudatus sowie im Mäusegehirn um 18.00 Uhr auf. Während der Dunkelperiode wurde die größte Toxicität gegenüber i.v. bzw. i.p. injiziertem ACh bei Mäusen gefunden. Ähnliche zeitliche Unterschiede ergaben sich für Neostigmin, Pilocarpin und Oxytremorin. Die Toxicität von Carbachol zeigte Maxima bei 12.00 und 24.00. Für Physostigmin, einen CholinesteraseHemmstoff mit einem tertiären Stickstoff, lagen sowohl die Toxicitätsmaxima als auch die Toxicitätsminima in der Dunkelperiode. Die rhythmische Schwankung der Toxicität von i.p. verabfolgtem Atropin verhielt sich umgekehrt wie die der Cholinomimetica (außer Carbachol). Auch nach i.v. Applikation von Scopolamin und N-Methylatropin war ein entsprechender rhythmischer Einfluß auf die Toxicität nachweisbar. Die Vorbehandlung mit N-Methylatropin schwächte die Toxicität zwar ab, der Toxicitätsrhythmus gegenüber ACh und Physostigmin war aber nicht verändert. Die Toxicität von Cholinomimetica zeigt ein Maximum während der höchsten ACh-Konzentrationen im Gehirn und der höchsten Stoffwechselaktivität. Bei den anticholinergen Substanzen zeigte sich ein umgekehrtes Verhältnis. Die Beziehungen zum zentralen ACh-Gehalt sind unklar.
    Notes: Abstract Acetylcholine (ACh) levels were determined in rat midbrain and caudate nucleus and mouse whole brain in mature animals adapted 3 weeks to a programmed lighting schedule (08:00 to 20:00 h light; 20:00 to 08:00 dark). Peak ACh levels in the rat occurred at 24:00 h; in the mouse the peak at 06:00 h did not differ significantly from values obtained at 24:00 and 12:00 h. Significant trough values occurred at 12:00 h in rat midbrain and at 18:00h in rat caudate nucleus and mouse brain. In mice toxicity of I.V. and I.P. administered ACh is maximal during the dark. Neostigmine, pilocarpine and oxotremorine have toxicity patterns similar to ACh. Carbachol toxicity peaked at 12:00 and 24:00 h. With physostigmine, a tertiary anticholinesterase, peak and trough occurred during the dark. The atropine (I.P.) toxicity rhythm is a mirror image of the cholinomimetic rhythm (except for carbachol). I.V. scopolamine and atropine methyl nitrate patterns resemble atropine's but are less clear-cut. Atropine methyl nitrate pretreatment reduced ACh and physostigmine toxicity but did not alter the overall pattern. Cholinomimetic toxicity and brain ACh patterns are similar, peaking when metabolic activity is maximal. An inverse relationship holds for the anticholinergic drugs. The relationship to central ACh is uncertain.
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  • 10
    ISSN: 1432-0738
    Keywords: 2,2-Dichlorvinyl Dimethyl Phosphate ; Dichlorvos ; Vapona ; Metabolism ; Man ; Rat ; Mouse ; Hamster ; 2,2-Dichlorvinyl-dimethylphosphat ; Dichlorvos ; Vapona® ; Stoffwechsel ; Mensch ; Ratte ; Maus ; Hamster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung An Mäusen und Hamstern wurde die Exkretion und Retention der Radioaktivität nach Fütterung mit [1-14C-Vinyl]-Dichlorvos bestimmt. Außerdem wurde beim Menschen die Exkretion und Exhalation gemessen und die erhaltenen Werte mit den tierexperimentellen Daten von Rattenversuchen verglichen. Die Ergebnisse zeigen einen schnellen Stoffwechsel von Dichlorvos bei allen vier untersuchten Species. Die Dealkylierung zu Desmethyldichlorvos spielt bei der Biotransformation eine untergeordnete Rolle. Eine gewisse Ausnahme zeigen die Mäuse, bei denen 18,5 % der zugeführten Radioaktivität als Desmethyldichlorvos aufgefunden werden konnte. Bei allen Species kam es zu einer hydrolytischen Spaltung zu Dichloracetaldehyd, der weiter zu Dichloraetbanol reduziert wird. Der weitere Weg führt über die Ausscheidung als Glucuronid mit dem Harn. Ein Teil wird dechloriert und das14C-Atom als14CO2 oder14C-Hippursäure im Harn ausgeschieden. Im menschlichen Harn konnte Dichloraethanol nach Inkubation mitβ-Glucuronidase nachgewiesen werden, wenn hohe Dichlorvoskonzentrationen (38 μg/l) eingeatmet wurden. Auf dieser Basis könnte eine Überwachungsmethode gegen die Inhalation von zu hohen Dichlorvoskonzentrationen ausgearbeitet werden.
    Notes: Abstract The routes of excretion and retention of radioactivity following the ingestion of [1-14C-vinyl]dichlorvos by mice and hamsters have been determined. The excretion of radioactivity in urine and exhaled air of man has also been measured. The data have been compared with those for rats. The results indicate that metabolism is rapid in the four species. Dealkylation to desmethyldichlorvos is a minor route of biotransformation, except in the mouse, where desmethyldichlorvos constitutes at least 18.5 % of the administered radioactivity. Hydrolytic metabolism of dichlorvos occurs in all species and leads presumably to dichloroacetaldehyde which is further metabolized by (i) reduction to dichloroethanol and excretion in the urine as the glucuronide and (ii) dechlorination followed by incorporation of the carbon atoms into endogenous biosyntheses and excretion as [14C]carbon dioxide and [14C]hippuric acid in the urine. Dichloroethanol can be detected inβ-glucuronidase-treated urine after exposure of a human subject to high air concentrations (38 μg/l) of non-radioactive dichlorvos. This may form the basis of a method of monitoring the exposure of humans to high concentrations of dichlorvos.
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  • 11
    ISSN: 1432-0738
    Keywords: Ferrihexacyanoferrate (II) ; Rat ; Thallium ; Toxicity ; Metabolism ; Ferrihexacyanoferrat(II) ; Ratte ; Thllium ; Toxicität ; Stoffwechsel
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die Verabfolgung einer 2% igen kolloidalen Lösung von Ferrihexacyanoferrat (II) (FHCF) als Trinkwasser erhöht bei der Ratte die Ausscheidungsrate von intravenös injiziertem Tl2SO4 (mit 204Tl markiert) aus Leber, Nieren und Muskulatur auf das 2,8fache. Dieser Effekt ist zeitunabhängig. Die LD 50/30 d von intravenös injiziertem Tl2SO4 wird durch FHCF-Behandlung um das 2,3fache erhöht. Für diesen Schutzeffekt ist allerdings nur das während der ersten 24 Std verabfolgte FHCF verantwortlich. Diese Befunde weisen darauf hin, daß die Schäden bei der akuten Tl-Intoxikation sehr schnell irreversibel werden.
    Notes: Abstract The administration of a 2% colloidal solution of ferrihexacyano ferrate (II) (FHCF) as drinking water increases in the rat the excretion of intravenously injected Tl2SO4 (labelled by 204Tl) from liver, kidneys and muscles by a factor of 2.8. This effect is independant of time. FHCF-treatment increases the LD 50/30 d of intravenously injected Tl2SO4 by a factor of 2.3. This protection, however, is provided by FHCF only if administered during the first 24 hours. These findings suggest that the damage resulting from acute Tl-intoxication quickly becomes irreversible.
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  • 12
    ISSN: 1433-8580
    Keywords: Scalds ; Local cooling ; Rat ; Quantity of leucocytes ; Verbrühung ; Lokale Kühlung ; Ratte ; Verhalten der Leukocyten
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Untersuchungen an Ratten ergaben folgende Befunde: 1. Sofortige lokale Kühlung nach der Verbrühung beeinflußt bei der Ratte im untersuchten Zeitraum von 15 Tagen den Verlauf der Erkrankung gemessen am Parameter der Leukocytenzahl. 2. Die Kühlungszeit muß ausreichend lang sein. 3. Die Kühlung muß früh genug einsetzen, beim Versuchstier Ratte innerhalb 5 min nach Verbrühung. 4. Bei verspätetem Kühlungsbeginn läßt sich auch durch Verlängerung der Kühlungsdauer das Verhalten der Leukocytenzahl im Ablauf des Krankheitsgeschehens nach Verbrühung nicht beeinflussen.
    Notes: Summary Following results are obtained in experiments with rats: Immediate local cooling after scald had a significant influence on progress of “burn-disease”. Time for local cooling must be long enough, onset of local cooling early enough. It is not possible to restore the consequences of a late onset by prolongation of cooling.
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  • 13
    ISSN: 1432-0827
    Keywords: Growth ; Bone ; Rat ; Tetracycline
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé La vitesse de croissance normale en longueur de la métaphyse proximale du tibia est déterminée chez le rat Sprague-Dawley entre les âges de 20 et 100 jours, en utilisant la méthode à la tétracycline. Le taux de croissance ne varie que légèrement dans les groupes d'âges différents. Il est plus élevé chez les animaux jeunes et décroit considérablement en fonction de l'augmentation de l'âge. Les rats mâles présentent une croissance plus élevée que les femelles. Cette étude a pour but de mettre au point une méthode permettant de déterminer les facteurs expérimentaux, liés à la croissance en longueur du rat.
    Abstract: Zusammenfassung Die normale Längenwachstums-Geschwindigkeit der proximalen Wachstumsplatte der Tibia wurde bei Sprague-Dawley-Ratten in einem Alter zwischen 20 und 100 Tagen mittels der Tetracyclinmethode gemessen. Die Wachstumsgeschwindigkeit variierte nur wenig innerhalb der einzelnen Altersgruppen. Die Geschwindigkeit war bei jungen Tieren am höchsten und nahm mit zunehmendem Alter beträchtlich ab. Männliche Ratten wuchsen schneller als weibliche. Diese Arbeit dient als Grundlage, um die experimentelle Beeinflussung des Längenwachstums der Ratte abschätzen zu können.
    Notes: Abstract The rate of normal growth in length from the proximal growth plate of the tibia in the Sprague-Dawley rat was measured between 20 and 100 days of age using the tetracycline method. The growth rate varied only slightly within different age groups. The rate was highest in young animals and decreased considerably with increasing age. Male rats grew faster than female. This study is intended to provide a base for an evaluation of experimental influence on the growth in length of the rat.
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  • 14
    ISSN: 1432-2013
    Keywords: Intestinal Absorption ; Medium Chain Fatty Acids ; Kinetics ; Active Transport ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. The transport of14C-octanoate by rat small intestine was determined in vitro by a modification of the method of Semenza and Mühlhaupt, and in vivo by using isolated segments or a perfusion technique in conscious rats (Haberichet al., 1968). 2. The absorption capacity of14C-octanoate in the distal ileum was significantly lower than in the proximal jejunum. 3. 14C-octanoate injected into a jejunal segment appeared rapidly in portal venous blood reaching its maximal concentration 4 min after the injection. 4. The transport of octanoate showed a saturation effect with increasing concentrations after an incubation of 4 min. However, with constant concentrations of octanoate in the medium, the transport rate was constant for 8–10 min. A similar saturation effect was also demonstrated in vivo. Values for maximal absorption rate (V max) and the half-saturation constant (K m), calculated from the Lineweaver-Burk plot, were 1.0 μMol/min and 17.7 mM, respectively. 5. Accumulation of octanoate in tissue water was demonstrated. For example, after incubation for 40 min in a medium concentration of 0.1 mM, the tissue/ medium ratio was 2.75:1. 6. Cyanide (2×10−4 M) markedly diminished the absorption rate of octanoate. 7. The absorption of octanoate was competitively inhibited by caproic acid (C6) in vitro. The inhibition constant (K i), calculated from the Dixon plot, was 47 mM. 8. Simultaneous administration of glucose and octanoate in vivo did not affect the absorption rate of the fatty acid. 9. These results suggest that the intestinal absorption of octanoate is an energy-dependant active process.
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  • 15
    ISSN: 1432-2013
    Keywords: Diphosphate ; Rat ; Vitamin D Metabolism ; Intestinal Calcium ; Absorption ; Bone Mineralization ; Renal Functions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The metabolism and the organ distribution of double labelled vitamin D3 (1,2-3H-4-14C-cholecalciferol) has been studied in rats in which the bone mineralization and the intestinal calcium absorption have been inhibited by a large pose (10 mg P/kg s.c. for 7–14 days) of disodium ethane-1-hydroxy-1,1-diphosphonate (EHDP). The most striking difference found was a reduced accumulation of radioactive cholecalciferol and its metabolites in the kidney of EHDP-treated rats. It is unlikely that this effect was due to an unspecific alteration of the functional renal tissue since blood urea, glomerular filtration rate and renal plasm a flow remained unaltered by this dose of EHDP. The EHDP-treated rats were able to form the metabolite eluted with peak IV of the silicic acid chromatographic system, that is 25-hydroxycholecalciferol. In these vitamin D repleted rats fed a high calcium diet, the tritium deficient metabolite eluted with peak V (1,25-dihydroxycholecalciferol) was only found in the intestinal mucosa of both control and EHDP groups three days after the injection of radioactive cholecalciferol, and this in a very small amount. Therefore no definitive conclusion can be drawn as to a possible interference of EHDP treatment on the production of 1,25-dihydroxycholecalciferol. The change in the renal metabolism of vitamin D in rats treated with a rachitogenic dose of EHDP may be caused by the modifications of the calcium metabolism brought about by the diphosphonate. Its relation, if any, with the decreased calcium absorption remains to be established.
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  • 16
    ISSN: 1432-2013
    Keywords: Rat ; Hypothalamus ; Prolactin ; LH
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Plasma levels of prolactin and LH were measured by radioimmunoassay following electrochemical stimulation of the medial preoptic area (MPO) or the arcuate nucleus (Arc.N.) in pentobarbital anesthetized proestrous rats. Differences in the secretion pattern of prolactin and LH were observed when stimulated by means of acutely or chronically implanted electrodes. Acute implantation and stimulation of the MPO resulted in no change in serum prolactin levels, whereas stimulation by means of chronically implanted electrodes evoked a marked increase in serum prolactin. The general observation was that electrostimulation in the acute experiments causes a less sharp but more prolonged prolactin and LH release from pituitary than stimulation through chronically implanted electrodes.
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  • 17
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    Psychopharmacology 25 (1972), S. 218-228 
    ISSN: 1432-2072
    Keywords: Fighting ; Delta-9-Tetrahydrocannabinol ; Chlordiazepoxide ; Fixed-Interval ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The frequency with which electric shock to the feet elicited fighting in five pairs of albino rats was not altered significantly by intraperitoneal injections of delta-9-tetrahydrocannabinol (THC) in doses ranging from 0.064–6.4 mg/kg, although chlordiazepoxide reduced the frequency of such fighting in a dose-related manner. This finding held true despite manipulations of THC vehicle, injection-test interval, and the previous drug experience of the subjects. In contrast, doses of 4.0 mg/kg produced a striking reduction in lever-pressing maintained by an FI 60″ schedule of food reinforcement.
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  • 18
    ISSN: 1432-2072
    Keywords: Reserpine ; Neonatal Treatment ; Sexual Behaviour ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To investigate whether reserpine given in the critical period of sexual differentiation of the rat brain affects adult sexual behaviour, female and male rats were given a single injection of reserpine on the fourth day after birth, and their sexual behaviour was tested at maturity. In the 11 consecutive daily tests for spontaneous sexual behaviour the reserpine treated female animals showed fewer regular behavioural and vaginal oestrous cycles than the control animals. 19 % of the reserpinized and none of the control animals had prolonged oestrous behaviour without a coincident prolonged vaginal cycle. The reseptivity quotients of the reserpine treated animals were reduced. In the tests for hormone induced sexual behaviour after ovariectomy no statistically significant differences between the number of animals responding or between the receptivity quotients occurred. The tests for spontaneous sexual behaviour in males showed that the reserpinized animals needed fewer intromissions to ejaculate than the controls. The significance of these findings is discussed.
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  • 19
    ISSN: 1432-2072
    Keywords: Oxazepam ; Conflict Behavior ; Rat ; Maze
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Rats were tested in a Lashley III maze, the floor of which was heated. The animals had to learn to negotiate it in order to gain access to the unheated goal box. In the early period of training the animals were able to find the goal box rapidly and without error. Their performance then deteriorated, in a particular way which strongly evoked a conflict behavior. This deterioration in performance was progressively reduced by oxazepam administration (8 mg/kg/day).
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  • 20
    Electronic Resource
    Electronic Resource
    Springer
    Psychopharmacology 24 (1972), S. 449-455 
    ISSN: 1432-2072
    Keywords: Avoidance and Acquisition ; Methamphetamine ; Discrimination Learning ; CNS Stimulants ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Avoidance responses, extra responses (on avoidance lever) and wrong lever responses were measured in naive rats acquiring a discriminated avoidance in a 2 lever Skinner box, 30 min after methamphetamine (0.25, 0.5 and 1.0 mg/kg). The smallest dose was ineffective; 0.5 and 1.0 mg/kg significantly increased the number of avoidance responses. This increase was not associated with a significant increase in the two other responses studied. The progressive increase (from the first to second part of the acquisition session) in avoidance responses was not accompanied by a parallel increase in the other responses. The position discrimination and the discrimination of the presence or absence of the conditioned stimulus was observed to be better in the drug groups.
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  • 21
    ISSN: 1432-2072
    Keywords: Agressive Behaviour ; Apomorphine ; Testosterone ; Testes ; Hypophysis ; Adrenal Glands ; Thyroid ; Castration ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The weights of testes, prostates, adrenals, thymus and the pituitary of rats with apomorphine induced aggressiveness did not differ from those without aggressiveness. Postpubertal castration, adrenalectomy or thyroidectomy did not reduce the apomorphine induced aggressive behaviour, but a considerable reduction was found after hypophysectomy. Prepubertal castration significantly reduced, but did not completely abolish the proportion of aggressive rats, especially when castration was performed on the 5th day. Prolonged treatment of male, female and castrated rats with high doses of testosterone from the time of weaning increased the proportion of aggressive animals. Less intensive treatment and treatment of adult rats were ineffective.
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  • 22
    ISSN: 1432-2072
    Keywords: Chronic Nicotine ; Attention Task ; Arousal ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Male, Holtzman rats were trained extensively on an attention task which required them to respond with a single lever-press to a very short, variably presented stimulus for food reinforcement, but which also required them to inhibit inappropriate responses. After performance had stabilized, two groups were treated with either nicotine base (100 Μg/kg, s.c., t.i.d.) or saline for 4 weeks. The groups were crossed-over so that the first received saline and the second nicotine for an additional 4 weeks. A 3-week saline recovery period followed. Rats were tested on the attention task daily through all periods. Analysis of the data indicated that independent of the treatment-order, rats performed more efficiently under nicotine treatment than under saline conditions. The improvement in performance was most notable in the reduction of inappropriate responding during chronic nicotine treatment. The significance of the behavioral changes in relation to proposed nicotine-induced neurophysiological changes and the two-arousal hypothesis are discussed.
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  • 23
    ISSN: 1432-2013
    Keywords: Lactate Turnover ; l-Lactate14C (U) ; Hypoxaemia ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Lactate turnover was measured in 24 anesthetized rats using14C-U-(l) Lactate with the priming dose-infusion technique. 2. 14C Lactate in blood was determined with a specific radio-enzymatic micromethod. 3. Lactate turnover increases with blood lactate concentration in the range 0.5 to 3 mM. In a steady state system this relationship means that a new equilibrium may be achieved at a higher pool level, between lactate production and utilization. 4. Comparing available data in four mammalian species lactate turnover at normal lactate levels was found to be approximately constant when computed on a body surface unit basis.
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  • 24
    ISSN: 1432-2013
    Keywords: Thoracic Aorta ; Complex Dynamic Young's Modulus ; Age ; Serum Lipids ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In 2 groups of male albino rats (wistar-strain), 6 months and 18 months of age, dynamic Young's moduli in longitudinal direction were measured, at 5 different frequencies between 1 and 5 Hz. Each group consisted of 10 animals. Measurements were made at the natural length and at 1.2 times this length. From each animal several serum lipids were determined. It was found that: 1. measured at the natural length and 1.2 times this length, no significant difference of dynamic Young's moduli between both age groups could be demonstrated 2. concerning the dynamic Young's moduli there is significant interaction between stretch level and age 3. retraction was significantly smaller in the old rats than in the young ones 4. the old animals had a significantly higher serum lipid content than the young rats 5. no correlation between serum lipids and Young's moduli could be demonstrated.
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  • 25
    ISSN: 1432-2072
    Keywords: Forced Motility ; Motor Activity ; Brain Noradrenaline and 5-Hydroxytryptamine ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The levels of 5-HT and 5-HIAA in the rat brain were measured after 1, 6, 24 and 36 h of forced motility in a treadwheel. The results showed that 5-HT metabolism had already increased in the forebrain after 1 h of exercise but later also increased in the brain stem, especially in the mesencephalon-pons-medulla regions. These changes had almost entirely disappeared after 50 min of rest. The NA levels with and without monoamine oxidase inhibitor were measured in animals after 36 h of forced motility. The results indicated an increase in NA metabolism in the brain stem.
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  • 26
    ISSN: 1432-2013
    Keywords: Pulmonary Diffusing Capacity ; Alveolar-arterial O2 Pressure Difference ; High Altitude ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Steady-state pulmonary diffusing capacity for CO and alveolar-arterial O2 pressure differences were measured at hypoxia in growing rats adapted to a simulated altitude of 3500 m. The pulmonary diffusing capacity was significantly higher and the alveolar-arterial gradients were significantly lower in the adapted animals as compared with the controls exposed to hypoxia for the first time. The increased diffusing capacity could be explained entirely by the increase of blood O2 and CO capacity whereas the decrease of gradients might be explained by the increase of blood O2 capacity together with an increase of the arterio-venous O2 difference.
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  • 27
    ISSN: 1432-2013
    Keywords: Cardiac Output ; Blood O2 Dissociation Curve ; High Altitude ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In rats adapted to a simulated altitude of 3500 m cardiac output measured at hypoxia by the direct Fick principle was significantly lower than in the control animals (mean values 54.3 ml/min and 69.8 ml/min, resp.). The decrease of cardiac output was accompanied by an increase of arterio-venous O2 difference and a decrease of stroke volume in the adapted rats. It is suggested that the decrease of cardiac output might be related to the increase of hematocrit. The adapted rats also showed higher arterial and mixed-venous O2 content (both at hypoxia) and increased O2 capacity. Arterial O2 saturation of the animals previously exposed to simulated high altitude hypoxia was significantly higher (67.3% as against 61.2% in the controls). The standard O2 dissociation curve showed lower oxygen affinity in the blood of the adapted animals but no physiological advantage concerning the transport of O2 to the tissues was found. In another group of animals the Bohr factor was estimated and no difference was found between rat and human blood.
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  • 28
    ISSN: 1432-2013
    Keywords: Cardiac Hypertrophy ; Diffusion Distance ; High Altitude ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In growing rats adapted to a simulated altitude of 3500 m for about 4 weeks and in their controls the evolution of cardiac ventricular weight was followed. The increase of total ventricular weight found in the adapted animals can be attributed exclusively to the increase of right ventricular weight. In other adapted and control animals cardiac capillary densities, muscle fiber diameter and external capillary radius were estimated and fiber—capillary ratio and diffusion distance were calculated. There was an increase of capillary density together with a decrease of muscle fiber density, fiber-capillary ratio and diffusion distance in the right but not in the left ventricle of the adapted rats. The muscle fiber diameters, however, were larger in both heart ventricles of the rats exposed to a simulated high altitude, especially in the right ventricle. This indicates that true hypertrophy of the muscle fibers is mainly responsible for the increase of right ventricular weight. In the left ventricle, however, a hypertrophy of the muscle fibers together with a decrease of stroma components is demonstrated. The physiological importance of the shorter diffusion distance in the right ventricle of the high altitude adapted rats is discussed and it is suggested that the shorter diffusion distance may help to keep the tissue O2 partial pressure above the critical value, mainly also in extreme situations with high myocardial O2 consumption.
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  • 29
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    Cell & tissue research 126 (1972), S. 41-52 
    ISSN: 1432-0878
    Keywords: Pituitary ; Rat ; Oestradiol influence ; STH-cells ; Leucine incorporation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Pituitaries of male and female rats neonatally treated with oestradiol dipropionate were examined with light and electron microscopy, disc electrophoresis and in vitro C14-leucine incorporation. Single dose of oestradiol administered shortly after birth to male rats has an prolonged stimulative effect on LTH synthesis and release. This is expressed in the cell hypertrophy, proliferation of ER, increase of corresponding band density and higher rate of 14C-leucine incorporation. In females this effect was less pronounced. STH cell in the treated male pituitaries were degranulated, corresponding hormone band density significantly lowered and incorporation of 14C-leucine was reduced. This could be considered as an inhibitory effect of oestradiol on STH synthesis and release. Such effect was more expressed two than four months after treatment and is more pronounced in male than in female rats.
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  • 30
    ISSN: 1432-0878
    Keywords: Adrenal medulla ; Rat ; Cell types ; Secretion ; Influence of fixation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Das Nebennierenmark der Ratte wurde nach Anwendung verschiedener Fixationsmethoden untersucht. Nach Immersionsfixation mit Glutaraldehyd oder Osmiumtetroxyd finden sich in der Nebenniere sog. Mischzellen, helle Zellen, syncytiale oder plasmodiale Zellen, die von den Untersuchern als Artefaktbildungen angesehen werden. In allen Proben nach Perfusionsfixation wurden solche Artefaktbildungen niemals beobachtet. Bei Immersionsfixation wurde eine enge Beziehung zwischen Sekretgranula und Cytoplasmamembran beobachtet, was bei Perfusionsfixation selten der Fall war. Die heutigen Theorien über den Sekretionsmechanismus bei Nebennierenmarkzellen werden aufgrund der vorgelegten Ergebnisse diskutiert. Die Arbeit zeigt die wesentlichen Vorteile der Anwendung der Perfusionsfixation für die Untersuchung der Nebenniere.
    Notes: Summary The adrenal medulla of the rat was studied utilizing various methods of fixation. In adrenal medulla specimens after immersion fixation either with glutaraldehyde or osmium tetroxide, elements such as mixed, clear, syncytial, or plasmodial cells, believed to be of artifactual origin, are observed in all of this material examined. These elements are absent in the specimens prepared by perfusion fixation. In specimens prepared by immersion fixation, secretory granules are found in close proximity to the plasma membrane; this localization is infrequent after perfusion fixation. Current theories of the mechanism of secretion of adrenal medullary hormones are discussed on the basis of our results. This investigation demonstrates the advantage and necessity of perfusion fixation in the study of the adrenal medulla.
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  • 31
    ISSN: 1432-0878
    Keywords: Ependyma ; Brain ; Rat ; Glycogen-rich cells ; Electronmicroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ependyma of the lateral ventricle of the rat brain was investigated at different ages from 20 days to adulthood. A particular cell type occurs in the external wall of the ventricle, where the proliferative subependymal layer is present. These cells found at all ages studied, are characterized by a high content of glycogen, and a structure different of typical ependymal cells. A large number of nerve endings is situated in close vicinity of these cells, either free in the ventricle lumen, or sometimes ensheathed in the cells. No synapse was found between these endings an the glycogen-rich cells. These glycogen-rich cells undergo several modifications with age: their glycogen content is reduced in the adult, and they acquire a few cilia and gliofilaments. It is suggested that they represent a transitory differentiation of the ependyma, functionally linked with the proliferative subependymal layer.
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  • 32
    ISSN: 1432-0878
    Keywords: Spermiogenesis ; Rat ; Spermatids ; Manchette ; Microtubules
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The manchette or caudal tube has been examined in Stage 14 rat spermatids. The microtubules of the caudal tube have been found to be partially sheathed by smooth endoplasmic reticulum which appears to be continuous with the outer nuclear membrane of the redundant nuclear envelope. The microtubules in caudal regions of the manchette have been noted to be interconnected by links of unusual size and morphology. It is suggested that the caudal tube consists at this stage of development of two structures, membrane and microtubules and that the links between the microtubules appear to play a role in the structural order noted in the position of the tubules of the manchette. The possible significance of these links in relation to motility is discussed.
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  • 33
    ISSN: 1432-0878
    Keywords: Sympathetic nerve fibres ; Rat ; 5-HT-cells ; Habenular region (Lamina intercalaris ; Medial habenular nucleus)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The pineal gland of the rat is located near the brain surface and is via a slender stalk connected to lamina intercalaris which constitutes a cell formation between the habenular and posterior commissures, continuing to the subcommissural organ. The stalk and lamina intercalaris, like the pineal proper, exhibited a yellow, formaldehyde-induced fluorescence which showed the histochemical and pharmacological properties of 5-HT. All these structures were richly supplied with catecholamine-fluorescent nerves which could be further followed rostrally from lamina intercalaris, mixing with the non-fluorescent commissural fibres and stria terminalis, into the medial habenular nucleus in which they extensively supplied both blood vessels and non-fluorescent nerve cells. Cytospectrofluorometric and chemical analysis suggested that the fluorescent nerves stored noradrenaline. This was supported by the finding that they disappeared after bilateral cervical sympathectomy (as did the fluorescent nerves in the pineal complex). In the medial habenular nucleus also catecholamine-containing and 5-HT-containing nerves of central origin were present. The occurrence of a rich, peripheral sympathetic innervation in the medial habenular nucleus of the brain offers possibilities for a previously not observed sympathetic influence on this nucleus. Also the arrangement, and the apparent continuity of the sympathetic innervation in the pineal gland, the lamina intercalaris, and the medial habenular nucleus, suggests some functional interconnection or coordination between these structures.
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  • 34
    ISSN: 1432-0878
    Keywords: Cardiac muscle cells ; Rat ; Mitotic division ; Myofibril changes ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of the myocyte at all phases of mitosis as well as of early postmitotic cells has been studied in the myocardia of 14- and 18-day rat embryos and 5- and 7-day old rats. The myofibrils remain unchanged up to the late prophase. In prometaphase the majority of Z-disks in embryo myocyte myofibrils and considerable part of these disks in myofibrils of suckling rats are drastically disintegrated. This is followed by a progressive isolation and scattering of the myofilament bundles and of the whole sarcomeres during the subsequent phases of mitosis. Thick myofilaments seem to be unchanged but thin ones become frequently poorly outlined (mainly in embryos). The sarcoplasmic reticulum, including its typically differentiated subsarcolemmal cisternae, exhibits relatively few changes during mitosis. In the early postmitotic period there is a gradual restoration of contrast-rich Z-bands, interconnecting the previously isolated sarcomeres. Patterns of this process have much in common with early stages of myofibrillogenesis (appearance of subsarcolemmal “Z-bodies”, formation of skeins of thin filaments etc.). The cleavage furrow formation is either absent or considerably retarded up to the postmitotic period. Behaviour of some other organelles during myocyte mitosis has been described. Possible mechanisms and significance of the observed phenomena are discussed.
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  • 35
    ISSN: 1432-0878
    Keywords: Infundibulum ; Rat ; Ependymal and glial cells ; Inclusions ; Neuroglial synapses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Zahlreiche Ependymzellen des Recessus infundibularis und Gliazellen der Zona externa besitzen Fortsätze, die bis an den perivaskulären Raum der Kapillarschlingen des Portalplexus heranreichen. Die Ultrastruktur dieser Gefäßfortsätze wird beschrieben. Sie können verschiedenartige Einschlüsse enthalten: 1. große, runde osmiophile Einschlüsse (0,5–2 μ im Durchmesser), die als „lipid inclusions“ bezeichnet werden; 2. unregelmäßig geformte, granuläre Einschlüsse mit gleichmäßiger Elektronendichte (500 bis 2000 Å im Durchmesser); 3. rundliche Granula mit einem hellen Zentrum und ringartig um dieses Zentrum gelagerten elektronendichten Körnchen (1200–1600 Å im Durchmesser). Der letztgenannte Granulatyp scheint ein charakteristisches Merkmal der Gefäßfortsätze in der Zona externa der Wistar-Ratte zu sein. Meist häufen sich die Körnchen gemeinsam mit den anderen beschriebenen Einschlüssen in den kolbenförmigen Endigungen der Gefäßfortsätze. Exocytosevorgänge an der dem perivaskulären Raum zugewandten Oberflächenmembran der Fortsätze weisen auf eine Abgabe von Substanzen an die Blutbahn hin. Neurogliöse Synapsen finden sich im Infundibulum vorwiegend zwischen Nervenfasern des Tractus tuberohypophyseus und Gefäßfortsätzen der Ependym- und Gliazellen. Der synaptische Spalt enthält häufig fädige oder körnige Strukturen. Solche Partikel finden sich zusammen mit tubulären oder vesikulären Membranprofilen auch im synapsennahen Bereich des Glia- oder Ependymfortsatzes. Die funktionelle Bedeutung dieser Synapsen insbesondere für die Abgabe neuronaler Substanzen wird diskutiert.
    Notes: Summary Many ependymal cells of the infundibular recess and many glial cells of the external layer send their processes to the perivascular space of capillary loops of the portal plexus. The ultrastructure of these vascular processes is described. They may contain various inclusions: (1) large, osmiophilic globules (0,5–2 μ in diameter), mostly termed “lipid inclusions”; (2) irregularly formed, granular inclusions with an evenly distributed content (500–2000 Å in diameter); (3) circular granules comprising an electron-lucent centre surrounded by an annular wall of electron-dense particles (1200–1600 Å in diameter). This type of granule seems to be characteristic for the vascular processes in the external layer of the Wistar rat. Frequently accumulations of these granules are found together with other inclusions in the widened end-feet of the vascular processes. The occurrence of exocytosis at the perivascular surface membrane of the vascular processes indicates a release of substances into the blood. Neuro-glial synapses in the infundibulum are mainly found between nerve fibres of the tuberohypophyseal tract and the vascular end-feet of ependymal and glial cells. The synaptic cleft often contains filamentous or granular material. Together with tubular and vesicular membrane profiles such particles are also found in the postsynaptic area of the ependymal and glial processes. The functional significance of these contacts is discussed particularly with respect to the release of neuronal substances.
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  • 36
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    Cell & tissue research 130 (1972), S. 171-179 
    ISSN: 1432-0878
    Keywords: Tubuli seminiferi ; Rat ; Structure ; Contractility ; Organ culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Isolated pieces of seminiferous tubules of adult rats were grown in organ culture for up to 8 weeks in Petri dishes on the surface of nutrient agar. The medium consisted of newborn calf serum, Eagle's minimum essential medium, glutamate and antibiotics. This method allowed observation of the contractions of the seminiferous tubules in the culture. Contractility, light and electron microscopic structure and histochemically demonstrable activities of alkaline phosphatase and ATPase of the tubule walls were studied at 1-week intervals. The contractility and alkaline phosphatase activity were maintained in the tubule wall for 3 weeks, and the activity of ATPase was maintained for 5 weeks. The thin filaments of the myoid cells, which are responsible for the contractility, were seen with the electron microscope in tubules cultured for 5 weeks. The organ culture method described in the present paper seems to be valuable for studies concerning the functioning of the myoid cells of the seminiferous tubules and the possibility that this is regulated by hormones.
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  • 37
    ISSN: 1432-0878
    Keywords: Neurosecretion ; Neurohypophysis ; Neurosecretory granule ; Rat ; Membranes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Neurosecretory granules (NSG) of rat posterior pituitary glands were prepared by differential centrifugation techniques mainly according to the procedure as described by Barer, Heller and Lederis (1963). As revealed by electron microscopy, the recovery of neurophysin and the contents of enzymes, purified NSG were obtained in a pellet at 30 000 g/60 min (0.44 M sucrose). Eighteen h after injection of (35S) cysteine into the supraoptic nucleus 60% of the recovered radioactivity in the neural lobe was found in the NSG, whereas 20% was found in the final supernatant (100 000 g/120 min). Sixteen days after injection the NSG and the final supernatant fraction contained fairly equal amount of (35S) cysteine (approximately 40%). It is suggested that after a period of intragranular maturation neurophysin is extruded into an extragranular pool of neurosecretory material. With the use of conventional polyacrylamide-gel electrophoresis it was shown that the predominating proportion of radioactivity in the NSG after a hypothalamic injection of (35S) cysteine was located within the neurophysin fraction A and in fraction B. Fraction B is suggested to be partly bound to the NSG membranes. When the NSG soluble and NSG insoluble proteins, obtained after lysis of NSG, were separated on polyacrylamide gels in the presence of sodium dodecylsulphate, the highly radioactive soluble protein was shown to consist of two components with average molecular weights of 12 300 and 14 600. Most of the proteins in the lysate were found in the NSG membranes, though less radioactive. A component with a mol.wt. of 37 000 was enriched in the membrane fraction. At longer times after isotope injection the high mol.wt. proteins, particularly those of the NSG membranes, contained increased amounts of radioactivity.
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  • 38
    ISSN: 1432-0878
    Keywords: Neurosecretion ; Pituitary gland ; Rat ; Neurophysin ; Vasopressin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The release of neurophysin from neural lobe tissue slices and isolated neurosecretory granules of the rat was studied at various time intervals after injection of (35S) cysteine into the supraoptic nucleus. For hours after isotope injection the release of radioactive neurophysin from neural lobe tissue was increased by depolarizing concentration of potassium in the presence of calcium ions. Fourteen and 30 days after isotope injection the release of radioactive neurophysin was relatively decreased in a medium of high potassium concentration which might be explained by the heterogeneity of the pool of neurophysin within the neural lobe. Four h after isotope injection the “spontaneous” release of neurophysin from neural lobe tissue was higher in dehydrated rats than in controls, and the neural lobes of these animals did not respond with an increased release of radioactive neurophysin when exposed to high potassium concentration. Eighteen h after isotope injection the predominating proportion of neurophysin-bound radioactivity was found in the neurosecretory granule fraction, whereas 14 days after injection a fairly equal amount of radioactivity was found in this fraction and in the “soluble” protein fraction. This indicates that with time an increasing amount of radioactive neurophysin passes from an intragranular to an extragranular pool. The spontaneous release of radioactive neurophysin from isolated neurosecretory granules was higher, and the increase of release upon exposure to an ATP-regenerating system was higher 14 days after isotope injection than 18 h after injection. This may imply that the neurosecretory material undergoes an intragranular “maturation” process to become more easily releasable. The release of radioactive neurophysin was inhibited in the presence of AMP and EDTA, which demonstrates the dependence of the release process of an ATPase and, probably, of calcium ions. Neurosecretory granules from dehydrated rats possessed a higher spontaneous release than those of control rats 18 h after injection, which may indicate an enhanced intragranular “maturation” process of the neurosecretory material due to osmotic stimulation.
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  • 39
    ISSN: 1432-0878
    Keywords: Surface multivesicular structures ; Erythrocyte maturation ; Rat ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Surface multivesicular structures associated with the plasmalemma of erythrocytes were observed in the peripheral blood of rats which have a significant number of circulating reticulocytes. These surface structures appear as ovoid evaginations (0.2 to 0.7 μ in diameter) of the plasma membrane and contain numerous small vesicles ranging from 0.05 to 0.1 μ in diameter. The structures were present during the final stages of maturation of erythrocytes, after nuclei and mitochondria had been extruded and only a few polysomes and small vesicles remained. They appear quite distinct from the autophagic vacuoles which have been described in association with degeneration and extrusion of mitochondria from erythrocytes. The exact origin of the small internal vesicles of these surface multivesicular structures is unknown; however, similar vesicles have been observed in the cytoplasm of the maturing erythrocyte especially in the vicinity of the Golgi body. These structures suggest a process by which Golgi elements and other small cytoplasmic vesicles are extruded during the late stages of maturation of rat erythrocytes.
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  • 40
    ISSN: 1432-0878
    Keywords: Diabetes insipidus ; Rat ; Hypothalamo-neurohypophysial system ; Synthesis of hormones ; Light- and Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The general ultrastructural features of the hypothalamo-neurohypophysial system in rats with hereditary hypothalamic diabetes insipidus (DI-rats, Brattleboro strain) are described. There is no decisively distinguishing difference between the neurons of the supraoptic and paraventricular nuclei. The neurons of both nuclei show signs of active protein synthesis. The perikarya of the neurons are markedly hypertrophic, the nuclei are large and the nucleoli prominent. In the cytoplasm there are numerous ribosomes, abundant rough-surfaced endoplasmic reticulum and extensive Golgi complexes. However, very few neurosecretory granules are to be seen. The axons of the hypothalamo-neurohypophysial tract are likewise enlarged and the paucity of neurosecretory granules is a striking feature also in the area of the tract. The majority of nerve endings in the posterior pituitary of DI-rats are devoid of neurosecretory granules. Microvesicles are abundant in the nerve endings and there are findings which suggest that microvesicles are involved either in endoor exocytosis. The signs of active protein synthesis and the concomitant paucity of neurosecretory granules are interpreted to imply transportation of the secretory proteins in an extragranular phase. The possible mode of release of the secretory proteins from the nerve endings and the role of microvesicles therein are discussed.
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  • 41
    ISSN: 1432-0878
    Keywords: Pituitary ; Rat ; Pars intermedia ; Adrenocorticotropin ; Immunohistochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Adrenocorticotropin (ACTH) was localized in the intermediate lobes of normal rat pituitaries with unlabeled antibody and the soluble peroxidase-antiperoxidase complex at the electron microscopic level. All of the intermediate lobe cells (light and dark cells) stained positively for ACTH. Stain of varying intensity was found on secretory granules and vesicles. Structures which resembled rough endoplasmic reticulum stained where the secretory granules and vesicles were most numerous. No stain was on mitochondria, in nuclei, in cisternae and granules of Golgi complexes, or in rough endoplasmic reticulum where there were few secretory granules. There were distinct immunohistochemical differences between the pars intermedia and anterior lobe ACTH cells. In the ACTH cells of the anterior lobe, the Golgi complex and its granules stained strongly, but not at all in the pars intermedia cells. This suggests that ACTH may not be packaged or condensed in the Golgi region of the latter.
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  • 42
    ISSN: 1432-0878
    Keywords: Neurohypophysis ; Rat ; Perivascular cells ; Neurosecretion ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The purpose of this study is to investigate the ultrastructural features of perivascular cells as found in the neural lobe of the hypophysis. In particular, an inquiry was made into the nature of the relationship of such cells to neurosecretory fibers and endings. The latter, in fact, are often invaginated within the perivascular cells and enveloped by their processes; furthermore, they often reveal a certain number of empty granules as well as characteristics of degenerative nature. In the course of this study the localization of the perivascular cells has been investigated as well as that of their processes within the extensive interlobular network typical of the hypophysial neural lobe of rodents. Based on the data gathered, the hypothesis is put forward that the perivascular cells play an important role in the turnover of neurosecretory endings, both under physiological and experimental conditions, contributing thereby to the release of post-hypophysial hormones.
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  • 43
    ISSN: 1432-0878
    Keywords: Basement membrane labyrinths ; Spinal cord ; Central canal ; Rat ; Light- and Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Die Wand des Zentralkanals im Rückenmark der weißen Ratte enthält zahlreiche Basalmembranlabyrinthe; ihre Zahl nimmt in caudaler Richtung deutlich zu. Die Perjodsäure-Bisulfit-Aldehydthionin-Färbung (Specht) gestattet ihren lichtmikroskopischen Nachweis. Die Labyrinthe stehen in Verbindung mit den Basalmembranen der kanalnahen Kapillaren. Sie können auch elektronenmikroskopisch identifiziert werden; ihre Struktur gleicht der der Basalmembranen der Gefäße. Die funktionelle Bedeutung der Basalmembranlabyrinthe wird diskutiert.
    Notes: Summary The wall of the central canal of the spinal cord of the white rat contains numerous basement membrane labyrinths, their number increasing towards the end of the canal. The period-acid-bisulfit-aldehydethionine-method (Specht) permits their light microscopic finding. They are in connection with the basement membranes of the capillaries situated near the canal. The basement membrane labyrinths can be identified by electron microscopy; their structure is similar to that of basement membranes of the capillaries. The functional significance of these structures is discussed.
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  • 44
    ISSN: 1432-0878
    Keywords: Gonocytes ; Rat ; Mitotic activity ; Autoradiography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Die Gonocyten der Ratte können in 2 hintereinander geschaltete Keimzellarten gegliedert werden, die I-Gonocyten und II-Gonocyten. Die I-Gonocyten proliferieren bei der Wistarratte zwischen 15. und 18. Fetaltag, die Tochterzellen der I-Gonocyten, die II-Gonocyten treten nach einer Zeitdauer von 7–8 Tagen zwischen 4. und 6. Lebenstag in die Mitose. Auf Grund der gewonnenen Daten erschien es sinnvoll, die mitotische Aktivität der II-Gonocyten und die Bestimmung der Dauer ihrer S-Phase an 5 Tage alten Ratten durchzuführen. Untersuchungen von 50 Zentren mitotischer Aktivität in einem in Serie geschnittenen Hoden einer 5 Tage alten Ratte ergaben, daß 148 von 190 Mitosen, d.s. 78%, in Gruppen und 122, d.s. 64% der Mitosen in „Paaren“ vorkommen. Mit der Methode der markierten Mitosen (Quastler u. Sherman, 1959) und der Methode der Doppelmarkierung (Hilscher u. Maurer, 1962) wurde die Dauer der S-Phase der II-Gonocyten bei 5 Tage alten Ratten bestimmt. Es ergab sich eine gute Übereinstimmung der nach beiden Methoden bestimmten Werte. Die S-Phasen-Dauer der II-Gonocyten dürfte danach am 5. Lebenstag bei 11,0–11,5 Std liegen.
    Notes: Summary The gonocytes of the rat are of two types: I-gonocytes and II-gonocytes. In Wistar rat I-gonocytes proliferate at the beginning of prespermatogenesis between the 15th and 18th day of gestation. Their multiplication stops between the 18th and 19th day. Starting on the 4th postnatal day, II-gonocytes, the daughter cells of I-gonocytes, begin to proliferate. The 5th postnatal day proved to be favourable for studying the mitotic activity and for determing the S-phase of II-gonocytes. In one serially sectioned testis of a 5 days old rat 25 sex cords were reconstructed. Till now 50 centres of mitotic activity of II-gonocytes with 190 mitoses were localized. Only 42 out of the 190 mitoses were isolated, 148 occur in groups. 122 out of the grouped mitoses are in “pairs”. That means that 78% of the grouped and 64% of all mitoses were to be found in pairs. By the method of labeled mitoses (Quastler and Sherman, 1959) and by the method of double labeling with C-14- and H-3-thymidine (Hilscher and Maurer, 1962) the duration of the S-phase of II-gonocytes were determined in 5 days old rats. The results of both methods show that the S-phase is 11.0 to 11.5 hours.
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  • 45
    ISSN: 1432-0878
    Keywords: Neurohypophysis ; Rat ; Exocytosis ; Freeze-etching ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Neural lobes of rats subjected to severe acute haemorrhage under sodium pentobarbitone anaesthesia were examined electron microscopically and the ultrastructure compared with that in anaesthetised and unanaesthetised controls. Changes in the localisation and numerical distribution of elementary granules and small vesicles in the neurohypophysial nerve endings of bled rats were consistent with the occurrence of exocytosis. The occurrence of “exocytotic profiles” was observed more frequently in freeze-etched tissue samples as compared with the material fixed for conventional electron microscopy. The ratio of small vesicles: elementary granules was shown to be significantly increased (P〈0.005) in the nerve endings of neural lobes from bled rats. Equally, the numbers of exocytotic profiles related to 1000 μm2 of neurohypophysial tissue area were significantly greater (P〈0.005) in bled rats.
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  • 46
    ISSN: 1432-0878
    Keywords: Accessory optic system ; Rat ; Blood vessels ; Extracellular space ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Two types of capillaries were found in the medial terminal nucleus of the rat accessory optic system. Type one capillaries are surrounded by glial processes and lack a perivascular space, whereas the type two capillaries and arterioles show a distinct extracellular perivascular space often filled with collagen fibrils. An internal as well as an external basal lamina lines these spaces. No fenestration of the endothelium was observed.
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  • 47
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 125 (1972), S. 415-431 
    ISSN: 1432-0878
    Keywords: Synapses ; Rat ; Cerebral cortex ; Glutaraldehyde/E-PTA ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Synaptic junctions in intact rat cerebral cortex have been examined following glutaraldehyde fixation and phosphotungstic acid (PTA) staining. In the presynaptic ending the network has a hexagonal arrangement, while the dense projections are regularly placed along the presynaptic membrane. Cleft densities occupy the intracleft region. The postsynaptic thickening extends uninterrupted along the length of the junction. Qualitatively, the majority of junctions fall into the ‘discontinuous-continuous’ category, in which the internal coat of the presynaptic membrane together with its associated dense projections is discontinuous along the length of the junction, whereas the postsynaptic thickening is continuous. By contrast, a small number of junctions are ‘continuous-continuous’. In an attempt to analyze the junctions quantitatively, nine indices were measured. Histograms of the size distributions of seven of these appear to be bimodal, and from this it is concluded that two junction populations may be distinguishable on quantitative grounds. It is also shown that the distance separating dense projections at the presynaptic membrane is of the order of 10–15 nm. This surprisingly low value has consequences for current ideas on the relationship between synaptic vesicles and dense projections, and these are discussed at length.
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  • 48
    ISSN: 1432-0878
    Keywords: Renal medulla ; Rat ; Interstitial ground substance ; Fixation ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Das Interstitium des inneren Nierenmarkes von Ratten wurde nach Anwendung verschiedener Fixierungsarten und Versuchsanordnungen elektronenmikroskopisch untersucht. Neben Bindegewebszellen und kollagenen Fibrillen enthält der interstitielle Raum bandförmige, basalmembranartige Strukturen, in deren weiträumigen Maschen zwei weitere Komponenten, nämlich ein feingranuläres und feinfilamentäres Material sowie kontrastreiche, globuläre Partikel liegen. Diese beiden Formelemente stellen sich bei den verschiedenen Fixierungsarten und Versuchsanordnungen unterschiedlich dar. Bei der feingranulären und feinfilamentären Komponente handelt es sich wahrscheinlich um interstitielles Blutplasma. Diese Deutung wird gestützt durch die morphologische Ähnlichkeit mit dem Blutplasma der Blutgefäße, die unterschiedliche Darstellbarkeit nach Glutardialdehyd-und Formalinfixierung sowie durch die Befunde nach Gefäßperfusion und Nierenvenenstauung. Das Verhalten der globulären Partikel nach OsO4-Einwirkung steht in Einklang mit der schon früher gegebenen Interpretation als präzipitierte saure Mukopolysaccharide. Ihr elektronenoptisches Bild wird im Vergleich zur bekannten makromolekularen Struktur der Mukopolysaccharid-Protein-Moleküle diskutiert.
    Notes: Summary The interstitial ground substance in the inner medulla of the rat kidney is examined electron microscopically after fixation with various fixation agents and under different experimental conditions. The papillary interstitium contains besides interstitial cells and few collagen fibrils basement membrane like material and two other components, fine granular-fibrillar elements and globular particles with heavy contrast. The appearance of the two latter interstitial components varies according to the different fixation agents used and to the experimental conditions. The fine granular and fine fibrillar material surrounds the globular particles numerously after glutardialdehyde-fixation but scarcely after formaldehyde-fixation. It increases after renal vein occlusion, but is diminished or absent, if the kidney is rinsed bloodfree. These results allow to conclude that this material represents interstitial bloodplasma. The behaviour of the globular particles after OsO4-fixation agrees well with the earlier interpretation according to which they represent precipitated acid mucopolysaccharides. Their electron microscopic appearance is discussed in comparison with the known macromolecular structure of the acid mucopolysaccharides.
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  • 49
    ISSN: 1432-0878
    Keywords: Spermiogenesis ; Rat ; Spermatids ; Manchette ; Microtubules
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The manchette or caudal tube has been examined in Stage 14 rat spermatids. The microtubules of the caudal tube have been found to be partially sheathed by smooth endoplasmic reticulum which appears to be continuous with the outer nuclear membrane of the redundant nuclear envelope. The microtubules in caudal regions of the manchette have been noted to be interconnected by links of unusual size and morphology. It is suggested that the caudal tube consists at this stage of development of two structures, membrane and microtubules and that the links between the microtubules appear to play a role in the structural order noted in the position of the tubules of the manchette. The possible significance of these links in relation to motility is discussed.
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  • 50
    ISSN: 1432-0878
    Keywords: Median eminence ; Rat ; Neurovascular contacts ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the median eminence of the rat axons of the supraoptic-paraventricular-hypophyseal tract with elementary neurosecretory granules (150–200 mμ) traverse the internal zone. Terminals containing dense core vesicles 60–120 mμ in diameter end on the portal capillaries of the median eminence. A unique organisation of the primary portal capillaries is shown. Endothelial cells have many fenestrae. The pericapillary space has numerous extensions all of which represent a special zone around the endothelial tube. The fine structural organisation and function of the neurovascular contacts in the median eminence are discussed.
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  • 51
    ISSN: 1432-0878
    Keywords: Hippocampal region ; Rat ; Monoamine oxidase ; Chemoarchitectonics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. The distribution of monoamine oxidase (MAO) in the hippocampal region of the rat has been studied in cryostat sections with the tryptamine-tetrazolium method of Glenner et al. 2. The staining pattern was rather diffuse as compared with the distribution of MAO in the guinea pig and of other enzymes in the rat hippocampal region. 3. However, there were differences in enzyme activity between different areas and layers which could be correlated to some degree with results obtained with other methods, e.g., silver impregnation, catecholamines, and acetylcholinesterase.
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  • 52
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 127 (1972), S. 201-208 
    ISSN: 1432-0878
    Keywords: Spermatogenesis ; Rat ; Mitosis ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The pattern of intercellular cytoplasmic bridges between rat spermatogonia and between spermatocytes is illustrated from electron microscopy of serial sections. Clones, or syncytia, containing as many as 22 connected spermatogonia and as many as 74 connected spermatocytes were observed. The absence of closed rings of cells agrees with the observation that intercellular bridges are the result of incomplete cell division, rather than cell fusion. The bridges thus are a record of spermatogonial divisions within a clone. In early spermatogonial generations there is a predominantly linear arrangement. The groups of spermatocytes have more side branches. From the presence of synaptonemal complexes it is concluded that the connected spermatocytes of a given clone are in about the same developmental stage. The pattern of intercellular bridges indicates, however, that not all nuclei in a clone undergo mitosis in the same cycle. The connected cells of a clone are therefore not all of the same generation. From unconnected bridges it is assumed that new clones originate from single cells or groups of spermatogonia which separate from an existing clone.
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  • 53
    ISSN: 1432-0878
    Keywords: Skeletal muscle ; Rat ; Fat droplets ; Fat resorption ; Quantitative electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Elektronenmikroskopisch nachweisbare Neutralfettpartikel kommen im M. tibialis anterior der Ratte vorwiegend in den mitochondrienreichen Fasern vom Typ C in der Nachbarschaft von Mitochondrien vor. Nach Glutaraldehyd-Osmium-Fixierung und Epon-Einbettung sind diese Partikel meist dielektronisch, seltener teilweise oder ganz adielektronisch. Auf 100 μm2 Schnittfläche durch C-Fasern findet man 3–4 Anschnitte von Fettpartikeln. Der mittlere Durchmesser der Anschnitte (d) ist 0,69 μm, der mit der graphischen Methode von Hennig bestimmte mittlere Durchmesser der Fettpartikel (d′) 0,80 μm. 2 h Narkose mit Pentobarbital beeinflussen weder Anzahl noch Durchmesser der Anschnitte. Nach 2 h Resorption von Maiskeimöl ist die Zahl der Anschnitte unverändert, der mittlere Durchmesser der Anschnitte bzw. der Partikel hat um etwa 20 % zugenommen (d=0,83 μm; d′=0,95 μm). Das entspricht einer Zunahme des morphologisch nachweisbaren Neutralfettes um 70 %. Da keine Pinocytose von Chylomikronen zu beobachten ist, wird angenommen, daß freie Fettsäuren durch das Plasmalemm in die Muskelfaser eindiffundieren und im Bereich vorhandener Fettpartikel als Triglyceride gespeichert werden.
    Notes: Summary In the anterior tibial muscle of rats triglyceride droplets predominantly appear within fibres rich in mitochondria (type C). In electron micrographs 3–4 of such droplets are present per 100 μm2 sectional area of C-fibres. The mean diameter of sections through fat droplets (d) is 0.69 μm, the mean diameter of the droplets (d′) as determined by Hennig's graphical method is 0.80 μm. Anaesthesia with pentobarbital (2 h) does affect neither number nor size of the particles. 2 h after application of corn oil into the stomach the number of fat droplets is unaltered, but the mean diameter has increased by 20 % (d=0.83 μm; d′=0.95 μm), corresponding to an increase of the volume of about 70 %. Pinocytosis of chylomicrones by muscle fibres has never been observed. Therefore it is supposed, that free fatty acids have passed the plasmalemma by diffusion and are incorporated into triglycerides and stored within pre-existing fat droplets.
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  • 54
    ISSN: 1432-0878
    Keywords: Lateral preoptic area ; Hypothalamus ; Rat ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The arcuate nucleus, median eminence, and the lateral preoptic area from the brains of aldehyde-perfused male and female rats were examined by electron microscopy. In the lateral preoptic area, three neuronal types are described: a small light neuron, a larger light one, and a dark neuron resembling the larger light one in size and nuclear shape. Many myelinated axons are interposed among single neurons or neuronal pairs. The relationship of structures to each other is discussed. Several observations not previously reported are illustrated from tissue of the arcuate nucleus and median eminence.
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  • 55
    ISSN: 1432-0878
    Keywords: Prechiasmatic gland (Organon vasculosum laminae terminalis) ; Rat ; Nerve endings ; Dense-cored vesicles ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary On the basis of the present electron microscopic study of the rat median vascular prechiasmatic gland, the unmyelinated nerve fibers containing dense-cored vesicles may be classified in three categories. (1) Nerve endings containing isomorphic rounded dense-cored vesicles, 800–1600 Å in diameter with a predominance of vesicles between 1100 and 1300 Å. These vesicles are synthesized in the nerve cell perikarya which are localized principally in the lamina profunda of the outer subpial layer and also in the neuropil of the inner glial covering layer. One or more “cholinergic” axon terminals are in contact with the surface of these nerve cell perikarya. The dense-cored vesicles travel in the axonal process which branches into an extensive terminal network characterized by the presence of small varicosities. They abut on the pericapillary spaces but never against another neuron or effector cell. A few nerve processes course between the ependymal cells and terminate in the preoptic recess of the third ventricle. The dense-cored vesicles may contain one of the primary monoamines. (2) Nerve endings containing pleomorphic dense-cored vesicles, 500–1600 Å in diameter with a predominance of vesicles between 800 and 1100 Å. The latter granular vesicles are associated with small, clear-centered vesicles, 260–550 Å in diameter, which are often aggregated in the vicinity of thickenings of the plasma membrane and of cytoplasmic dense projections. The intercellular space and the cell plasma membrane, however, do not display any modification facing these structures. Synapse-like contacts are observed between these nerve endings and cells containing a great amount of microfilaments and glycogen particles in their cytoplasm. The latter cells possibly represent processes of ependymal cells. (3) Nerve endings containing a few large dense-cored vesicles in addition to a majority of synaptic vesicles.
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  • 56
    ISSN: 1432-0878
    Keywords: Olfactory tubercle ; Rat ; Degeneration ; Synapse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The olfactory tubercle of the rat was studied by electron microscopy both in the normal and after ipsilateral olfactory bulb ablation at survival times of from 14 hours to seven days. Particular emphasis was placed on synaptic structures and their changes following the lesion. Normal synapses are similar to those described in previous studies and presynaptic profiles are of at least three types. Types-A and -B contain round vesicles and form asymmetrical contacts and type-C profiles contain flattened vesicles and form symmetrical contacts. There appear to be two major types of degenerative changes. The electron-lucent type predominates at early survival times and is seen first at 14 hours. These profiles show an early reduction in numbers of vesicles with mitochondrial swelling followed by shrinkage of the profile. These profiles become increasingly electron-dense at later survival times. The second major type of degenerating profile is initially electron-dense. The earliest changes in these profiles are an increased axoplasmic density and increased microtubular density and clumping without apparent loss of vesicles. These profiles also become progressively more electron-dense at longer survival times. The observations are discussed in relation to previous reports.
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  • 57
    Electronic Resource
    Electronic Resource
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    Cell & tissue research 124 (1972), S. 217-229 
    ISSN: 1432-0878
    Keywords: Sensory axons ; Dorsal root ganglia ; Rat ; Ribosomes ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the dorsal root ganglia of the rat, ribosomes were found not only in the initial segment, but they were also observed in the axoplasm of intraganglionar myelinated fibres and in the sensory portion of spinal nerves. Axons of seven-days-old rats contained more ribosomes than those of adult animals. The amount of particles decreased gradually from the initial segment trough intraganglionar internodes to the axons of spinal nerves. No ribosomes were found in axons of dorsal roots. In intraganglionar fibres, ribosomal particles were usually observed near the nodes of Ranvier, in the vicinity of Schmidt-Lantermann clefts and in axons near the Schwann cell nuclei. They were arranged in tetrads, pentads or in larger polysomes, and they were often observed adjacent to a group of mitochondria. The particles had invariably a stable size, their average diameters measuring 234 ± 2 × 197 ± 3 Å, which is practically equal to the diameters of 232 ± 2 × 203 ± 3 Å of ribosomes in the Schwann cell cytoplasm. These values fall within the range of diameters of ribosomes isolated from various cells of eukaryotic organisms as given in the literature. Since no other granular component of the cytoplasm has similarly stable dimensions, the measurements are considered to prove that the axonal particles described here are ribosomes.
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  • 58
    ISSN: 1432-0878
    Keywords: Macrophages ; Microtubules ; Enamel organ ; Rat ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the enamel organ of rat incisors macrophages are present in the zone of matrix formation, the transitional zone, the enamel maturation and pigmentation zone. The macrophages accumulate adjacent to redifferentiating amelocytes in the transitional zone. The macrophages phagocytize fragments of disintegrating amelocytes. In addition to the well known complement of organelles the macrophages present an elaborated microtubular system, scattered, thick filaments, a cortical feltwork of thin filaments, and spherical nuclear bodies. The microtubules emanate from “attached” and free pericentriolar satellites and radiate aster-like towards the cell surface or into pseudopods or curve along the nuclear surface for long distances, often related to nuclear constrictions. It is suggested that the microtubular system plays a prominent role in directional movement of the macrophages. The cortical filaments, if contractile, may create the cytoplasmic flow necessary for the cell motility.
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  • 59
    ISSN: 1432-0878
    Keywords: Median eminence ; Rat ; Exocytosis ; Micro-pinocytosis ; Releasing factors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Exocytosis has been demonstrated by electron microscopy in the external zone of the median eminence of the rat. Exocytotic profiles have been observed in nerve fibres characterized by the presence of granular vesicles with median diameters of 90–103 nm and agranular vesicles of about 50 nm. In addition to the small agranular vesicles, coated vesicles of the same size have been found in many nerve fibres, suggesting that at least part of the agranular vesicles in the median eminence originate by micro-pinocytosis. The nature of the fibres showing exocytosis is discussed. Attention is drawn to the possibility of identifying types of fibres in the median eminence by the occurrence of exocytosis.
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  • 60