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  • 11
    ISSN: 1432-0568
    Keywords: Endometrium ; Oviduct ; Rabbit ; Estrus ; Scanning electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The surface profile of the mucosae of rabbit uteri and Fallopian tubes during estrus were examined under the scanning electron microscope. We found that the endometrium forms interconnecting circularly arranged pillows, short mounds and ledges. Straight, continuous, longitudinal folds do not occur. Ciliated cells are found abundantly in the cavum epithelium, occurring either singly or in small groups. The oviducal mucosa in the ampullary region forms tall, unbranching, longitudinally aligned folds. Secondary and tertiary folds are not found. A complicated system of low lying slanting, diagonal mucosal ledges forms between the tall longitudinal folds. They connect neighbouring longitudinal folds together.
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  • 12
    ISSN: 1432-0568
    Keywords: Parotid gland ; Miniature pig ; Electron microscopy ; Innervation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This communication reports on the morphology of the parotid gland of miniature pigs (Göttingen strain). 1. The glandular system consists in its terminal portions of acinar secretory parts. Between the basal lamina and the secretory epithelial cells myoepithelial cells are located. 2. The cytoplasmic organization of the acinar cells represents the features of mucous secretory cells. By electron microscopic means, light secretory granules have been demonstrated which frequently are coalescent. Between the bulk of secretory material only small remnants of cytoplasm are visible. The electron dense nuclei are located in basal parts of the cells. Intercellular canaliculi have not been observed. 3. The intercalary ducts, located between the acinar portions and the striated ducts of the gland, are long and narrow tubules, frequently branched. Their epithelium is simple cuboidal, and there is no indication of any secretory activity. 4. The epithelium of the striated ducts is simple columnar. The orientation of mitochondria parallel to the cell axis, and also the invaginations of the basal cell membrane give the basal cytoplasm a vertically striated appearance. 5. The paravascular nerves of the gland's connective tissue consist of bundles of unmyelinated axons. These branch into smaller bundles, and finally into single unmyelinated axons which reach the acinar portions. These axons appear to be only partly surrounded by Schwann cells. Very thin axons alone penetrate the basal lamina and reach the secretory cells of the acini; moreover, these axons may occasionally reach the intercellular spaces between the secretory cells. Within these terminal parts of the axons groups of synaptic vesicles appear.
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  • 13
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract: Based on the Berger–Simons holonomy classification, we characterize all Riemannian spin manifolds carrying a twistor spinor with at least one zero. In particular, the dimension n of the manifold is either even or n=7. Outside the set of zeros of the twistor spinor the metric is conformal to either a flat metric or a Ricci flat and locally irreducible metric.
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  • 14
    ISSN: 1420-8903
    Keywords: Primary 51M20 ; Secondary 57M50
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Summary Abstract regular polytopes are complexes which generalize the classical regular polytopes. This paper discusses the topology of abstract regular polytopes whose vertex-figures are spherical and whose facets are topologically distinct from balls. The case of toroidal facets is particularly interesting and was studied earlier by Coxeter, Shephard and Grünbaum. Ann-dimensional manifold is associated with many abstract (n + 1)-polytopes. This is decomposed inton-dimensional manifolds-with-boundary (such as solid tori). For some polytopes with few faces the topological type or certain topological invariants of these manifolds are determined. For 4-polytopes with toroidal facets the manifolds include the 3-sphereS 3, connected sums of handlesS 1 × S 2 , euclidean and spherical space forms, and other examples with non-trivial fundamental group.
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  • 15
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    Springer
    Periodica mathematica Hungarica 39 (2000), S. 161-183 
    ISSN: 1588-2829
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract A triangulation of a manifold (or pseudomanifold) is called a tight triangulation if any simplexwise linear embedding into any Euclidean space is tight. Tightness of an embedding means that the inclusion of any sublevel selected by a linear functional is injective in homology and, therefore, topologically essential. Tightness is a generalization of convexity, and the tightness of a triangulation is a fairly restrictive property. We give a review on all known examples of tight triangulations and formulate a (computer-aided) enumeration theorem for the case of at most 15 vertices and the presence of a vertex-transitive automorphism group. Altogether, six new examples of tight triangulations are presented, a vertex-transitive triangulation of the simply connected homogeneous 5-manifold SU(3)/SO(3) with vertex-transitive action, two non-symmetric 12-vertex triangulations of S 3 × S 2, and two non-symmetric triangulations of S 3 × S 3 on 13 vertices.
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  • 16
    ISSN: 0025-5874
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract. We classify the hypersurfaces of revolution in euclidean space whose second fundamental form defines an abstract pseudo-Riemannian metric of constant sectional curvature. In particular we find such piecewise analytic hypersurfaces of class C 2 where the second fundamental form defines a complete space of constant positive, zero, or negative curvature. Among them there are closed convex hypersurfaces distinct from spheres, in contrast to a theorem of R. Schneider (Proc. AMS 35, 230–233, (1972)) saying that such a hypersurface of class C 4 has to be a round sphere. In particular, the sphere is not II-rigid in the class of all convex C 2 -hypersurfaces.
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  • 17
    ISSN: 1432-0878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Die Glandula lacrimalis der Ziege ist eine tubulo-acinöse Drüse vom serösen Typus, deren Zellen unterschiedliche Formen aufweisen. Lichtmikroskopisch lassen sich dunkle und helle Zellen unterscheiden. Die dunklen enthalten regelmäßig PAS-positiv reagierende Substanzen. Das Epithel der Ausführungsgänge ist kubisch bis zylindrisch, teilweise erscheint es zweireihig. Auch elektronenmikroskopisch lassen sich verschiedene Zelltypen unterscheiden. Die supranukleären Zellbereiche sind mit Sekretvakuolen unterschiedlich strukturierten Inhalts angefüllt. Die apikale Zellmembran wird durch kurze Mikrovilli vergrößert. Außerdem wurde das Verhalten zahlreicher Hydrolasen und Oxydoreduktasen histochemisch untersucht. Die starke Fermentaktivität der Aldolase und Laktat-Dehydrogenase in Drüsen- und Gangepithelien und der relativ hohe Gehalt an histochemisch nachweisbarer G-6-PDH in den Drüsenzellen werden diskutiert.
    Notes: Summary The lacrimal gland of the goat is a tubulo-acinar gland of serous type. The glandular epithelium consists of dark and light cells. The dark cells are rich in PAS-positive material. The ducts are lined with a cuboidal or columnar epithelium; the larger ducts have a double-layered epithelium. Electronmicroscopical investigations show that the apical two-thirds of the cells are occupied by numerous light and dark secretory vacuoles in various stages of maturation. Short microvilli project into the lumen. Also reactions of numerous enzymes (hydrolases and oxydoreductases) were checked up. The strong reaction of ALD and LDH in the gland cells as well as in the ductular cells and the relatively high amount of G-6-PDH in the gland cells are discussed.
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  • 18
    ISSN: 1432-0878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Histologische, histochemische und elektronenmikroskopische Untersuchungen an der Glandula lacrimalis des Rindes ergaben folgende Resultate: 1. Die Tränendrüse des Rindes ist eine verzweigte tubulo-acinöse Drüse vom seromucösen Typ. Sie besitzt echte Schaltstücke mit flachen bis kubischen Epithelzellen. 2. Alle Drüsenzellen enthalten PAS-positive (rote) Sekretgralnua (neutrale Mucopolysaccharide). Einige färben sich dagegen auch mit Alcianblau und Astrablau an (saure Mucopolysaccharide). 3. Intra- und interlobuläre Ausführungsgänge sind von einem einschichtigen, hoch zylindrischen Epithel ausgekleidet. Im Epithelverband der großen interlobulären Gänge kommen PAS-reaktive Becherzellen vor. 4. Die Zellen der Drüsentubuli und endständigen Acini sind kegelförmig und sitzen einer dünnen Basalmembran auf. Es werden auch hier typische Myoepithelzellen beobachtet. 5. Der Peinbau der Drüsenzellen wird durch die Ansammlung sekrethaltiger Vakuolen im mittleren und apikalen Cytoplasma der Zellen bestimmt. Die Sekretgranula, die im Lichtmikroskop PAS-positiv und alcianophil sind, werden von einfachen Membranen umhüllt, die teilweise unterbrochen sein können. Ihr Inhalt ist entweder feinflockig, granulär oder völlig homogen. 6. Die zylindrischen Epithelzellen der Ausführungsgänge wölben sich apikal pilz-oder ballonartig in die Lichtung vor. 7. In der Tränendrüse des Rindes wurden eine Reihe von Hydrolasen sowie zahlreiche Oxydoreduktasen aus der Glykolysekette, dem Zitronensäurezyklus, der Atmungskette und dem Pentosephosphatzyklus mit histochemischen Methoden nachgewiesen. Die Befunde werden mit früheren Ergebnissen aus der Tränendrüse von Hund, Katze, Ziege und Schaf verglichen und diskutiert. 8. In der Glandula lacrimalis des Rindes scheint dem Zitronensäurezyklus die größere Bedeutung als Energiequelle zuzukommen.
    Notes: Summary Histological, histochemical and electron microscopical investigations of the lacrimal gland of the cattle had the following results: 1. The lacrimal gland of the cattle is a branched tubulo-acinar gland of sero-mucous type. Intercalated ducts, connecting the intralobular ducts and the terminal secreting acinar cells, are composed of flat low cuboidal epithelium. 2. All the gland cells contain PAS-positiv granules (neutral mucopolysaccharides). Some of these cells are rich in alcianblue and astrablue reactive material (acid mucopolysaccharides). 3. The intra- and interlobular ducts are lined by a single layer of columnar epithelial cells. In the epithelium of the interlobular ducts goblet cells can be demonstrated. 4. The tubuli and acini are lined with pyramidal epithelial cells, which rest on a thin basement membrane. Myoepithelial cells are located between the base of the epithelial cells and the basement membrane. 5. The fine structure of the acinar cell is characterized by an accumulation of secretion containing vacuoles in the middle and apical cytoplasm of the cell. These secretion granules, which are PAS-positive in the light microscope, are often bounded by ill-preserved membranes. Their internal structure is electron lucent or electron dense, sometimes characterized by a flocculent graininess. 6. The epithelium of the ducts consists of a single layer of columnar cells. Their apical plasma membranes form frequently balloons into the lumen. 7. In the lacrimal gland of the cattle a number of hydrolases and oxidoreductases of the glycolytic chain, the citric acid cycle, the respiratory chain, and the hexose monophosphate shunt are demonstrated by histochemical means. The findings are discussed with previously obtained data of canine, feline, goat and sheep lacrimal glands. 8. In the lacrimal gland of the cattle the citric acid cycle seems to have the greatest importance as an energy source.
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  • 19
    ISSN: 1432-0878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Die Tränendrüse des Hundes ist eine mucöse, tubulo-acinäre Drüse. Die Endstücke münden in Ausführungsgänge, die Streifenstücken gleichen. Die Drüsenzellen sind zylindrisch und mit dicht beieinander liegenden Sekretvakuolen angefüllt, deren Inhalt aus elektronenmikroskopisch dichten, feingranulären oder netzartigen Strukturen besteht. Basal liegen Zellkern, Mitochondrien, Lamellen des endoplasmatischen Retikulums und Golgi-Apparate. Zwischen den Sekretvakuolen liegen Cytoplasmasepten, in denen RNS-Granula, manchmal Mitochondrien und lamellenartige Strukturen beobachtet werden. Die Sekretvakuolen färben sich mit Astrablau, Alcianblau, Rutheniumrot und mit der PAS-Reaktion intensiv an (saure Mucopolysaccharide). Die Ausführungsgänge ähneln den proximalen Harnkanälchen der Niere. Die Mitochondrien sind in Säulen angeordnet, dazwischen liegen die Einfaltungen des basalen Plasmalemms. Die Epithelien der Ausführungsgänge besitzen hohe Aktivitäten der Enzyme LDH, SDH, NADH-T-Red, NADPH-T-Red und Cytochromoxydase.
    Notes: Summary The general structure of the dog lacrimal gland — a mucous gland — consists of acini, tubuli and striated ducts. The acini and tubuli are composed primarily of pyramidal shaped cells, whose major portion consists of locules of a slightly electron dense substance with a delicate open network of fine dense strands. This area presumably represents mucin. At the base of the cell are crowded the nucleus, mitochondria, endoplasmic reticulum and Golgi membranes. The vacuoles of mucin are delineated by compressed strands of membranes, cytoplasmic granules and occasional mitochondria. Staining of paraffin sections in Astrablue, Alcianblue, Ruthenium-Red and PAS revealed the presence of large positive granules (acid mucopolysaccharides). The ducts are closely similar to the proximal convoluted tubules of the kidney. The mitochondria are numerous, elongated and are oriented in the long axis of the columnar cell. The base of the cells is highly cleft by deep infoldings of the plasma membrane. The enzyme pattern of the epithelial cells of the ducts is characterized by high activities of LDH, SDH, NADH-T-Red, NADPH-T-Red and cytochrome oxydase.
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  • 20
    ISSN: 1432-0878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Die menschliche Glandula lacrimalis ist eine tubulo-acinöse Drüse und besitzt mehrere Ausführungsgänge. Ihr fehlen Schaltstücke sowie Sekretrohre; die verzweigten Tubuli münden direkt in intralobuläre Ausführungsgänge. Histologisch und histochemisch sind zwei Zelltypen zu unterscheiden: sog. G-Zellen mit zahlreichen, sehr großen Granula, und sog. K-Zellen, die vorwiegend kleine Sekretkörnchen in geringer Menge enthalten. Alle Drüsenzellen verhalten sich PAS-positiv. Die G-Zellen (Drüsenzellen mit großen Sekretkörnchen) sind außerdem reaktiv auf Alcianblau, Astrablau, Rutheniumrot und nietachromatisch nach Toluidinblau. Hierbei handelt es sich demnach um saure Mucopolysaccharide enthaltende Sekretgranula. Die Feinstruktur zeigt den typischen Bau sekretorischer Zellen. Das basale Ergastoplasma ist stark entwickelt und erinnert an das Zellbild eiweißproduzierender Zellen. Augenfällig ist die Fülle von Golgi-Strukturen, die ohne Bevorzugung bestimmter Zellbezirke überall im Cytoplasma verteilt sind. Die zahlreichen Mitochondrion sind auffällig groß. Die supranucleären und apikalen Zellbezirke sind fast völlig vom kugeligen, ovoiden und häufig stark verformten Sekretvakuolen unterschiedlicher Größe ausgefüllt. Ihr Inhalt ist teilweise hell und strahlendurchlässig, teils fein, teils grob granuliert, teils elektronendicht, osmiophil und homogen. Die luminalen Plasmamembranen sind entweder glatt oder mit kurzen, stummeiförmigen Mikrovilli besetzt. In der menschlichen Tränendrüse wurden zahlreiche Hydrolasen und eine Reihe von Oxydoreduktasen aus der Glykolysekette, dem Zitronensäurezyklus, der Atmungskette und dem Pentosephosphatcyklus histochemisch nachgewiesen. Das Enzymmuster gleicht dem der Kaninchen-Tränendrüse. Die Befunde werden diskutiert.
    Notes: Summary The human lacrimal gland is a tubuloacinar organ consisting of three rather distinct compartments: acini, tubuli and excretory ducts. Two of these compartments, the acini and tubuli, are the sites of secretory activity. There are two types of secretory cells: K-cells with large granules and G-cells containing a few of very small granules. Histochemically, acinar cells are uniformly characterized by a basal dense basophilia and PAS-positive material in the apical two thirds of the cytoplasm. In contrast, the granules of the G-cells are positive for Alcian blue, Astra blue, Ruthenium red and Toluidine blue. Electron microscopic studies have demonstrated further dissimilarities between these two cell types. If the vertical axis of an acinar cell is divided into four equal zones, it can be found that the basal zone always contains most of the rough-surfaced endoplasmic reticulum, the nucleus lies within the next zone, and the apical half of the cell is filled with secretory material of varying density and a number of scattered Golgi areas. Golgi profiles are most abundant in the granule-containing apical half of the cell but also occur near the nucleus and occasionally in the lateral areas of the basal zone. Secretory granules are bound by ill-preserved membranes. Their internal structure is partly electron lucent, partly electron dense, occasionally characterized by a flocculent graininess. Plasma membranes take different contours on various surfaces of the cell. Bordering the lumen they are relatively even but form a few microvilli. Acinar cells have many mitochondria, some of which may be rather large. Also the distribution pattern of some hydrolases and of a number of oxydoreductases of the glycolytic chain, the citric acid cycle, the respiratory chain and the hexose monophosphate shunt is reported for the human lacrimal gland. The enzyme patterns were similar to those observed in the rabbit.
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