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  • Life and Medical Sciences  (2,378)
  • 1970-1974  (2,378)
  • 1
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The cervicothoracic muscles of nymphal and adult Euborellia annulipes (Lucas) are described, the former for the first time. In the adult, eight new muscles are identified, while the nymphs possess a further seven muscles that disappear at maturation or before. Otherwise the same muscles occur in nymphs as in adults, though some nymphal muscles are less clearly separated from one another than their adult homologs. The attachment sites of certain muscles show a number of slight differences between nymphs and adults. The work emphasizes the necessity of taking the immature musculature into account in assessing the muscular pattern represented in an insect order.
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  • 2
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 144 (1974), S. 11-21 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The morphological features of the hemocytes of the crustacean Ligia exotica are similar to hemocytes of insects and millipedes. Jones system of hemocyte classification is extended to crustacean hemocytes. As in insects, seven classes of hemocytes, identified as prohemocytes, plasmatocytes, granular hemocytes, cystocytes, oenocytoids, spherule cells and adipohemocytes, occur. The prohemocytes can be subdivided into five categories that probably represent the precursor of major cell types. The structural and chemical features of other major cell classes are distinct and support the concept of Jones ('62) that these types might have different lineages and might not be capable of transforming into one another. Some of the prohemocytes, plasmatocytes and granular hemocytes are amoeboid. Cystocytes do not bring about any visible plasma coagulation similar to their counterpart in millipedes. Oneocytoids and adipohemocytes are rare. Plasmatocytes, cystocytes and oenocytoids occur in conglomerates, the significance of which is discussed. The cell types are compared with those of the hemocytes of other crustaceans. It is suggested that the nomenclature based on morphological characters is more suited for crustacean hemocytes than a nomenclature based on behavioural and physiological characters.
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  • 3
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Some of the cytological characteristics of the hemocytes of the scorpion, Palamnaeus swammerdami, were studied. The morphological features of the arachnid hemocytes were observed to be similar to those of hemocytes of insects, millipedes and isopods. Jones' system of hemocyte classification was extended to the arachnid hemocytes. The six classes of hemocytes indentified in the scorpion correspond to prohemocytes, plasmatocytes, granular hemoocytes, cystocytes, spherule cells and adipohemocytes of insects. A cell type comparable to oenocytoids of insects and crustaceans is absent. The prohemocytes can be subdivided into four categories that probably represent the precursors of the major cell types. The cytological characteristics of the major cell classes and the occurrence of the miniatures of some of these major cell types support the concept of Jones (62) that these cell types might have different cell lineages and might not be capable of transforming into one another. Some of the prohemocytes, plasmatocytes and granular hemocytes were amoeboid. The nature of the granules and the vacuoles of plasmatocytes and granular hemocytes were compared with the granules and vacuoles of corresponding hemocytes of other arthropods. Cystocytes did not bring about any visible coagulation similar to their counterparts in millipedes and crustaceans. Plasmatocytes, granular hemocytes and spherule cells were observed to occur in conglomerates. The cell types noted in the present study were compared with the hemocytes of other arachnids.
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  • 4
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 144 (1974), S. 71-83 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The biomechanical role of the mammalian clavicle and the functional significance of the aclaviculate condition were investigated. Shoulder movements in rats (Rattus norvegicus) with excised clavicles were compared to those of normal rats by biplanar plate radiography. Shoulder movements during walking of the claviculate American opossum (Didelphis marsupialis), and aclaviculate raccoons (Procyon lotor) and cats (Felis domestica) were compared by biplanar cineradiography.The mammalian clavicle, where present in its complete form, exerts both a “spoke” and a “strut” effect on shoulder movement. By maintaining a fixed distance between the acromion and manubrium, the clavicle ensures that relative movement between these structures is arcuate. Aclaviculate mammals, in contrast, have linear shoulder excursions that are nearly parallel or slightly oblique to the median plane, depending on the conformation of the thorax. Medial collapse of the shoulder in aclaviculate rats demonstrates that the clavicle is under compression, and thus acts as a strut.Reduction or loss of the clavicle, which has occurred independently in numerous mammalian phylogenies, has been regarded as an adaptation for greater shoulder movement and hence increased stride. However, on present evidence clavicular reduction in cursorial mammals appears to be more directly related to a linear excursion of the shoulder joint and a restriction of limb movements to a sagittal plane.
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  • 5
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The tail of Teratoscincus scincus has dorsal scales that have tubercles on their dorsal and ventral surfaces. Sounds are produced when these rub past each other as the excited animal moves its tail. The relative movement of scales is intensified by caudal torsion. The frequencies of the sounds cover a range from 9 to 25 kops and thus, differ from those produced during vocalizations.
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  • 6
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 144 (1974) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 7
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A cardiaca-allatal commissural plexus (CACP) lies between and partly overlapping the postcommissural lobes of the corpora cardiaca (CC), the nervi corpori allati I (NCA I) and the corpora allata (CA). CACP, which is often continuous posteriorly with a complicated postallatal plexus (PAP), comprises a variable number of connectives with neurosecretory processes linking the cardiaca-commissural organ or dorsal cardiac commissure (containig tritocerebral fibres) to the NCA I. the allatal commissure and the CA. Neurosecretory processes are exchanged between the two halves of the cephalic neuroendocrine complex (CNC) both intracerebrally at different locales, possibly to ensure functional synchrony of CNC components.NCA I and CACP are drawn out with their stroma to varying extents over the CA. Histophysiological evidence suggests that part of the stainable secretion stored in, and or in axonal transit through CA may be released through CA surface; NCA I, the nervi cardiostomatogastrici, CACP, perhaps also NCA II may function as neurohaemal areas. A “directed” neurosecretory pathway could be distinguished from PAP to the foregut and the fat body. The degree of spatial intimacy detected between neurosecretory and stomatogastric components of CNC suggests that the two systems may function in an integrated fashion. The recurrent-oesophageal nerve complex serves not only for a direct transport of neurosecretion, but also as one of the sites of its release.
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  • 8
  • 9
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 142 (1974), S. 71-89 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Relationships between the cribriform plate of the ethmoid, the olfactory bulb, and olfactory acuity were explored using material from 13 of the 17 bat families.All megachiropteran cribriform plates were entirely perforated. In contrast, microchiropteran plates showed distinct perforated portions dorsally and nonperforated portions ventrally. The plates of frugivorous species had more foramina than those of insectivorous ones. Bats with mixed dietary habits were intermediate. Our data suggest that the Chilonycterinae were originally frugivorous, and have only secondarily reverted to an insectivorous diet.Trend analyses show that wherever dietary preference appears to favor a more acute sense of smell, bulb diameter tends to be larger. In general, frugivorous bats tend to have bulbs exceeding 2 mm in diameter; insectivorous bats tend to have bulb diameters of 2 mm or less. The number of foramina in the plates and total cribriform plate area tends to increase as a function of bulb area, but the plate area the foramina occupied increases as a function of bulb volume. The ratio of the size of the bulb to the size of the cerebral hemisphere does not predict olfactory acuity in bats.
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  • 10
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The fiber constituents and connections of the calyces  -  the input-receiving regions  -  of the corpora pedunculata (“mushroom bodies”) were studied in reduced silver preparations from the American cockroach, Periplaneta americana (L.). In the outer synaptic layer of the calyces five fiber classes were distinguished, the first three of which arise outside the mushroom body. (1) Four highly similar neurons with somata near the optic lobe branch into different parts of the ipsiateral protocerebrum, including both calyces. Their fibers are highly constant in arrangement and position and contain small nucleus-like bodies. (2) The tractus olfactorio-globularis (sensu lato) emits fiber groups which course along the calycal walls as “calycal tracts” before ultimately dissipating into the synaptic layer. Variability within these tracts is described. (3) Fibers of undertermined origin outside the mushroom body radiate from the calycal center outwards through the synaptic layer. (4) From the inner calycal layer of neurites belonging to intrinsic mushroom-body neurons, perpendicular collaterals enter the synaptic layer. (5) Intrinsic-neuron somata near the calycal rim emit fibers which course tangentially within the synaptic layer from calycal rim to center. These fibers form a special peripheral zone in the pedunculus.The predominant presumably afferent calycal fiber class is that derived from the tractus olfactorio-globularis. No evidence was found for tracts from optic lobe to calyces. On this basis, and in light of the experimental and comparative anatomical literature, it is suggested that the corpora pedunculata of P. americana and other pterygotes are fundamentally second-order antennal sensory processing centers.Conflicting observations in earlier reports are critically discussed.
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  • 11
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 142 (1974) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 12
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    Journal of Morphology 142 (1974), S. 91-107 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The number, location, size, shape and microstructure of the parathyroid glands of Agama agama agama, Hemidactylus brooki angulatus and Pytodactylus hasselquisti hasselquisti was investigated using approximately 250 specimens of each species from the Zaria area of Nigeria.Only parathyroid III was found. Additional patches of tissue in Hemidactylus, though possibly parathyroid IV, are considered to be derived from parathyroid III. It was found that the amount of parathyroid tissue per gram of body weight was similar in the three species used, and that females had more parathyroid tissue than males. The same situation seems possible in other species.The structure of the parathyroid glands could not be related to taxonomic grouping within the Sauria, but the general picture was found to be more similar to that of birds and mammals than to that of amphibians.
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  • 13
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    Journal of Morphology 142 (1974), S. 109-116 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Mast cells were demonstrated in eight species of snakes, using special fixation techniques to prevent solubilization of cytoplasmic granules. Toluidine blue O and azure A were the major stains and observations were made under light microscope including cytophotometric analysis.The mast cells of snakes were shown to be relatively small (7-11 μ in diameter) when compared to mast cells of a lizard (8-15 μ), dog and rat (9-15 μ).Among the various organs examined, mast cells were particularly numerous in the mesentery, tongue, underneath the serosa of the digestive tract and in the heart, between muscle fibers and in the epicardium.Although under the light microscope some snake mast cells seemed to be orthochromatically stained, when analysed by cytophotometry they were demonstrated to be actually metachromatic.Snake mast cells granules were demonstrated to have an amphoteric behavior, since they were stained with both basic (toluidine blue O and azure A) and acid dyes (eosin and ponceau-acid-fuchsin).
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  • 14
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    Journal of Morphology 142 (1974), S. 117-135 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Retinal projections were studied experimentally in the Northern water snake using modifications of the Nauta silver impregnation technique. Contralaterally, the retina projects to nucleus geniculatus lateralis pars dorsalis and pars ventralis, nucleus lentiformis mesencephali and nucleus geniculatus pretectalis. A sparse projection was also observed to nucleus ovalis. An additional afferent thalamic projection to nucleus ventrolateralis was found in two cases. The retina projects ipsilaterally to the dorsolateral portion of nucleus geniculatus lateralis pars dorsalis, and sparsely to nucleus lentiformis mesencephali and nucleus geniculatus pretectalis. Nucleus posterodorsalis receives dense bilateral retinal projections. Contralaterally, the retina also projects to the superficial layers of the tectum (layers 8-13 of Ramón) and to nucleus opticus tegmenti. Armstrong's findings that the retinal projections in Natrix are qualittatively similar to those in lizards were confirmed. However there are marked quantitative differences among the various pathways and their corresponding nuclei. These differences are particularly striking in comparing the visual projections to the dorsal thalamus, the retino-tecto-rotundal and the retino-geniculate systems. The first is reduced in volume and the second is markedly increased in volume in comparison with lizards. These data lend support to the theories of Walls that snakes evolved from fossorial lizards and of Underwood that the eyes of these lizards underwent reduction but not complete degeneration. Qualitatively the retinal projections are conservative among lizards and snakes, but a history of reduction of these pathways in ancestral snakes with a selective increase in the retino-geniculate system as a surface niche was reattained is reflected in the anatomy of this ophidian visual system.
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  • 15
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    Journal of Morphology 142 (1974), S. 137-152 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Fine structure of the torus semicircularis of the loach, carp, common eel and rainbow trout was studied by light and elecron microscopy. The torus semicircularis of each species is divided into four layers. The subependymal first layer comprises numerous unmyelinated fibers and their terminals which contain cored vesicles. The second and the third layers are composed of small cell bodies and their dendrites respectively. These layers develop equally in the four species and contain the usual axodendritic synapses. On the other hand, the fourth layer varies in different species. The mediumsized cells in this layer, which are inferred to be of the same origin as the small cells from their configuration and size, show differences in lamination in each species. Compared with the usual axodendritic synapse of the small cells, the medium-sized cells have quite different synaptic patterns, which include inhibitory and electrical as well as the usual excitatory chemical synapses. From these findings, the medium-sized cells are surmized to receive sound of different degrees of intensity from that received by the small cells, which may have an effect on feeding behaviors of the species. In the deepest portion of the torus semicircularis of all species, there are large multipolar cells on which numerous axon terminals synapse in much the same way as they do on the medium-sized cells. These findings suggest that the synaptic patterns in the torus semicircularis may depend not on the receptive cells in each layer but on the various characteristics of the afferent fibers.
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  • 16
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Abdominal extra-adrenal chromaffin tissue, or paraganglia, was examined at the ultrastructural level to elucidate the innervation of this adrenal medullary homologue. Paraganglia display unmyelinated nerve fibers surrounded by Schwann cell cytoplasm. These nerves are separated from the paraganglion Type I (granule-containing) cells by cytoplasmic projections of paraganglion Type II (satellite) cells. However, serial sections show that the nerves eventually make synaptic contact with the Type I cell. At the axon-chromaffin cell junction, only the outer aspect of the nerve is covered by the satellite cell. The presynaptic endings contain numerous synaptic vesicles, mitochondria and glycogen particles. The vesicles are predominantly of the clear-cored variety, but a few possess centers which are elecron opaque. The pre- and postsynaptic membranes are separated bya subsynaptic space and occasionally exhibit the membranal densities usually associated with synaptic areas. These ultrastructural studies establish definite evidence that abdominal paraganglion cells are innervated.
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  • 17
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    Journal of Morphology 142 (1974), S. 165-185 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The gland cells of Lyonet's gland, which is accessory to the silk gland in the silkworm larva, is characterized by the presence of complicated canaliculi bearing microvilli on their inner surface, large numbers of mitochondria and remarkably convoluted basal plasma membrane. On the other hand, the cell lacks the well-developed cytoplasmic membrane system such as rough- and smooth-surfaced endoplasmic reticula and Golgi bodies, though free ribosomes are numerous. Secretory vesicles are absent, and the canaliculi contain no dense material. From such ultrastructural observations, it was suggested that a possible role of the gland may be the exchange of the small molecules such as water and ions, rather than the hitherto supposed secretory role of a cementing sunstance of silk proteins. The lumen of the proximal part of the glandular duct contains a kind of proteinaceous substance which can be demonstrated histochemically and is regarded as similar to one of the silk proteins in the silk gland, not to the real product of the Lyonet's gland.
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  • 18
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 142 (1974) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 19
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Specimens, representative of each of the major taxa of mosquitoes, were fixed in copula and the external genitalia examined by scanning electron microscopy. The periphery of the basin-like everted aedeagus of Aedus aegypti precisely matches that of the everted atrial membrane of the female. These structures are appressed during coitus and sealed by pressure of the paraprocts, aedeagal pouch and proctiger. When everted, the aedeagus of male Culex pipiens reveals a ridged dome that surrounds the genital opening. This dome seals itself laterally into a gutter formed by pad-like extensions of the female's genital lips and is sealed dorsally by pressure of the aedeagal apodeme. The aedeagus of another culicine species, Wyeomyia smithii, bears the gonopore at the apex of a spined tube. This tube is inserted between the female's genital lips and is sealed within the genital atrium. The aedeagus of the toxorhynchitine species Toxorhynchitis brevipalpus is immobile and is inserted deep within the genital atrium of the female where it is sealed by pressure of the atrial walls. Males of each of these mosquitoes deliver a mixture of semen and sperm to the copulatory bursa of the female. After withdrawal of the aedeagus, sperm is transferred to the spermathecae.In contrast, sperm of Anopheles quadrimaculatus are delivered directly to the spermathecal duct. The tube-like aedeagus is positioned by its leaflets during sperm transfer and is driven deep into the atrium, where a mixture of semen and sperm is ejaculated.The significance of mechanical barriers to mating between species is discussed.
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  • 20
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The termite gut flagellates are of interest because of their unusual motile organelles, their ability to digest cellulose, and their symbiotic relationship with prokaryotes inhabiting the insect gut. This report provides a detailed ultrastructural description of Pyrsonympha from the hind-gut of Reticulitermes flavipes.The motile axostyle is composed of 2,000-4,000 microtubules connected by cross-bridges. At its anterior end, the axostyle is associated with a “primary row” of microtubules which is associated with a fibrous network. The “primary row” is embedded in a large mass of amorphous, electron-dense material occupying the furthest anterior end of the cell. The basal bodies of the eight flagella are also embedded in this presumptive microtubule-organizing center. The flagella are associated with the cell surface throughout their length. Isolation and reactivation of the axostyle has demonstrated that although ATP dependent motility is inherent in the structure of the axostyle, its proper control may be mediated by the attachment of the axostyle to structures at the anterior end of the cell.Pyrsonympha lacks morphologically distinguishable mitochondria and Golgi complexes. The cell surface is covered by unique, previously underscribed, tubular specializations. Symbiotic microorganisms are observed associated with the cell surface and within the cytoplasm.Wood particles are taken up from the gut fluid by large phagocytic vacuoles formed at the posterior end of the cell. Even during the process of breakdown, the wood is always enclosed within the membrane of the phagocytic vacuole.The Pyrsonympha from Reticulitermes flavipes are not attached to the lining of the hind-gut and do not contain an attachment organelle, unlike the Pyrsonympha from other species of Reticulitermes.
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  • 21
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 143 (1974) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 22
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 143 (1974) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 23
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    Journal of Morphology 143 (1974), S. 121-165 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The gecko ear was studied in 36 species belonging to 24 genera. This receptor has attained an advanced level of structure and performance in this group of lizards, but there are many variations among species. To a large extent these variations follow subfamily lines as represented in Kluge's system of classification.Brief consideration is given to features of the outer and middle ear, but chief concern is with inner ear structures and their relations to auditory sensitivity as represented by the cochlear potentials.The auditory papilla is segmented, with a dorsal portion whose hair cells have their ciliary tufts attached to a tectorial membrane, and a ventral portion in which these cells form tow assemblages, one with tectorial connections and the other with connections to a line of sallets.The dorsal segment varies greatly in length and in the form of ciliary orientation. In Eublepharinae and most Gekkoninae the ciliary orientation is unidirectional, and the degree of sensitivity relates to the length of this segment. In Diplodactylinae and Sphaerodactylinae the orientation is bidirectional, and this segment functionally hardly differs from the ventral segment.Auditory sensitivity as measured in terms of the cochlear potentials shows close relations with subfamily groupings, except for the Gekkoninae in which considerable diversity is found.The evidence from structural differentiation, along with that derived from the forms of the cochlear potential functions, leads to the suggestion that these ears possess a high degree of pitch discrimination and capability for the analysis of complex sounds.
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  • 24
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Mature mouse and cat peripheral nerve fibers have been examined in vitro by time-lapse photography. Some Schmidt-Lanterman clefts which were open at the start closed later; other were seen to open and then to close, some of them more than once. The implications of these movements are considered, especially in regard to the question of the passage of materials from the endoneurial connective tissue spaces to the axon.Myelin movements other than those occurring at the Schmidt-Lanterman clefts consisted primarily of the development and frequent regression of indentations of the myelin sheath. A single evagination was seen to develop and then to recede. These myelin movements suggest that previously described invaginations and evaginations of the myelin sheath, including flaps of “redundant myelin”, are not static but rather that they are in a state of movement, forming and regressing at intervals.The possible functional significance of the development and regression of myelin sheath indentations in relationship to axoplasmic flow is discussed.
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  • 25
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The authors describe the spermiogenesis of Polyxenus lagurus, a diplopod, in the male genital ducts and the transformations the spermatozoon successively undergoes in the spermatheca.The spermatozoon in the male genital ducts looks like a little barrel devoid of centriole and of any kind of rudimentary flagellum whatever. The organelles are markedly modified; cross sections present an elongated, flattened nucleus, an X-shaped body running parallel to it on the opposite side and two longitudinal mitochondrial strips interposed between them. The rest of this barrel-shaped spermatozoon is filled with peculiar Golgi formations, the spongy chambers, which open outwards through little vents.In the spermatheca the spermatozoon is quite different: it is shaped like a long ribbon. The basic structure of the spermatozoon is formed by the double folding of part of the cortical layer of the barrel-shaped spermatozoon. On the central part of this endo-skeleton are longitudinally ranged the nucleus and the acrosome flanked on both sides by a thread of mitochondria. Even in this phase the sperm has no flagellum.
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  • 26
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 143 (1974), S. 247-257 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Several secretory and nonsecretory enzymes were localized histochemically in the main venom gland of 13 viperid snakes. All secretory cells show the intracellular oxidative enzymes succinate dehydrogenase and monoamine oxidase. The granular reactions obtained for both enzymes resemble mitochondria in distribution. Distinctive cells with a very high succinate dehydrogenase activity are dispersed among the secretory cells of all species except Atractaspis.Nonspecific acid phosphatase activity is found in the supranuclear region of the secretory cells in species that do not secrete this enzyme and throughout the cytoplasm in snakes that secrete the enzyme. Nonspecific alkaline phosphatase activity occurs in the secretory cells of those snakes whose venom shows this activity. Leucine amino peptidase (aryl amidase) activity is found in the venom and in the secretory cells of all the species.In Vipera palaestinae both the venom and the secretory cells of the main venom gland contain nonspecific esterase, L-amino acid oxidase and phosphodiesterase activities. The localization of phosphodiesterase and L-amino acid oxidase do not show major differences between glands at different intervals from an initial milking.Adenosine-monophosphate phosphatase activity is localized in the supranuclear region of the secretory cells in the glands of Vipera palaestinae and Aspis cerastes. Its activity is found in the venom of Aspis only.
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  • 27
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 143 (1974), S. 259-283 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The male genital systems of two mysids, Archaeomysis grebnitzkii (subfamily Gastrosaccinae) and Neomysis awatschensis (subfamily Mysinae) are described. The testes of both species include a pair of central cords (spermatogonial cells), two sets of lateral sacs, and a set of dorsal-lateral spermatidic pouches in which spermiogenesis takes place. Mature sperm exit dorsally from the pouches into a common U-shaped seminal vesicle, the arms of which extend posteriorly as the right and left vasa deferentia.The emphasis of this study was on the follicle cell-spermatid relationship. Spermatids retain their own cell membranes as do the follicle cells. A bundle of sperm tails extends toward the follicle cell nucleus making several revolutions about the nucleus. Masses of rodlets occupy this tract with the spermatid tails. The tail consists of an outer cylinder with banding in a periodicity similar to collagen protein, and an inner cavity filled with a structureless, dark-staining material. Heads of the spermatozoa differ considerably between the two species. The elongate, reflexed head of Neomysis with its central filament joins the tail at an acute angle. The short cylindrical head of Archaeomysis with its anterior hood-like extension joins the tail directly. The distinctiveness of the sperm types might prove useful for taxonomic purposes. As noted by previous investigators, the number of spermatids per follicle cell shows specificity: Neomysis awatschensis has around 16 spermatids per follicle cell, Archaeomysis grebnitzkii about 100.
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  • 28
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Peripheral blood lymphocytes from three patients with defective differentiation of B cells were studied by routine electron microscopic techniques. One patient had severe combined immunodeficiency with rudimentary development of the B cell line. Two had immune deficits secondary to the B cell malignancy, chronic lymphocytic leukemia. Accumulations of tuboreticular structures were found in the cytoplasm of lymphocytes from the severe combined immune deficiency patient, sometimes in close association with annulate lamellae. The tuboreticular structures resemble those described in lymphocytes and endothelial cells of patients with systemic lupus erythematosus. In one patient with chronic lymphocytic leukemia, cylindrical arrangements of ribosomal material occupied the cytoplasm of many lymphocytes. These cylinders were observed in samples of blood drawn at different times and after tissue culture of lymphocytes with and without pokeweed mitogen. The other patient with chronic lymphocytic leukemia had circulating lymphocytes with material identified as IgM in the perinuclear spaces and dilated cisternae of the rough endoplasmic reticulum. This material sometimes had a crystalline structure.These observations indicate that in some cases functional immunological deficits in B cells, manifested by failure to differentiate to mature secretory cells, may be correlated with morphological aberrations of protein-manufacturing organelles within the cell.
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  • 29
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 140 (1974), S. 577-582 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The fate of cortical granules was ascertained in cold-shock activated rabbit eggs. Unfertilized oocytes were obtained 14 hours after intravenous injection of Human Chorionic Gonadotropin. Experimental oocytes were stored at 6 to 10°C for 24 hours in F10 medium containing 10% rabbit serum. Control oocytes, and the experimental ones subsequent to cold-shock treatment, were incubated for 24 hours. Formation of ‘pronuclei’ occurred in 6% of the cold-shock treated oocytes. None of the control oocytes were activated. Electron microscopic observations show that activation occurred without the dehiscence of cortical granule content into the perivitelline space. Cortical granules were dispersed in the cytoplasm or clumped together at the periphery. Occasionally, cortical granules were found discharged into the perivitelline space with the limiting membrane intact.
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  • 30
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The Karnovsky cholinesterase stain was used to map the positions of the myoneural junctions distributed over the inner surface of three frog sartorius muscles. In each preparation end-plates were seen to occur in clusters, predominantly associated with fine myelinated nerve fibers in proximity to the larger nerve branches. No myoneural junctions were observed in the extreme proximal or distal regions of the muscles. Although more junctions were found in the regions proximal to the point of nerve entry into the sartorius muscle, terminals were more consistent in their location in areas distal to this point. End-plate configurations varied appreciably in length, branching and complexity, but the majority of the terminal nerve processes extended parallel to the long axis of the muscle fibers.
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  • 31
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Using an immunoperoxidase technique at the ultrastructural level, vasopressin was localized in the axons of both the supraoptic and paraventricular nuclei, in the internal zone of the median eminence and the posterior pituitary but not in the perikarya of the neurosecretory neurons. A complete absence of histochemical reaction was found in the hypothalamo-neurohypophyseal tract of the rat with hereditary hypothalamic diabetes insipidus (Brattleboro strain).
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  • 32
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Extensive tight junctions are located between overlaps of plasma membranes of capillary endothelial cells. Micropinocytotic vesicles are few in number and are seen as invaginations on the A face and as protrusions on the B face. The freeze-fracture appearance of these cells is consistent with their thin section appearance and their role as the site of the blood-brain barrier.
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  • 33
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Human thyroid glands obtained within 2.5 hours of death were examined for the presence and distribution of calcitonin-containing cells using horseradish peroxidase as an indicator in an indirect immunohistochemical procedure. The glands were cut into 10 to 20 transverse slices per lobe and fixed in glutaraldehyde. A representative section of each paraffin-embedded slice was processed and systematically scanned for calcitonin-containing cells. Of 13 glands examined, ten contained calcitonin cells. The cells were found mostly in the follicular epithelium both singly and in groups. They were most numerous in the central region of each lobe of the gland. The isthmus and poles were devoid of calcitonin cells and only occasionally were these cells found at the surface. Parathyroid glands were examined by the same procedure for the presence of calcitonin cells but none were observed. These results demonstrate that calcitonin-containing cells are found regularly in human thyroid glands and that the distribution of these cells is centered in the central region of each lobe of the gland.
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  • 34
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A nidus of supraependymal cells was located within the infundibular recess of a rat's third ventricle. Upon transmission electron microscopic analysis, these cells were clearly identified as neurons. Neuronal processes, as well as end-terminals that contained dense-core and clear synaptic-like vesicles, were also observed coursing around these cells. It is suggested that some of the supraependymal cells that have been observed in previous scanning electron microscopic studies could be neurons similar to those described here.
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  • 35
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 140 (1974), S. 117-127 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Embryos from timed matings were studied at days 12-24 of gestation with respect to crown-rump length and external appearance. A linear increase in length was observed from the twelfth (2.5 mm) to the twenty-fourth (27.7 mm) day with the largest increases occurring between days 20 and 21 (3.8 mm) and days 22 and 23 (4.2 mm). The smallest daily increases were observed between days 15 and 16 (1.01 mm) and days 21 and 22 (1.03 mm), while the average daily increment for the remaining days was between 1.5 mm and 2.5 mm. Major changes in external appearance occurred on days 13, 14, 17 and 20 of gestation. Those features which could be observed externally were described for each of the days during the period studied. Late prenatal development in the gerbil resembles that of other myomorph rodents but proceeds at a slower rate than in other species such as the mouse or hamster. This slower rate of development may be of value when precise timing of drug administration and recovery of embryos is necessary.
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  • 36
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    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 140 (1974), S. 145-145 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 37
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 38
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The ultrastructure of a specialized encapsulated nerve ending located in the papillary layer of rat gingiva is described. The axon in the corpuscular ending possesses microvesicles and microtubules, and is surrounded by laminar cells (with basement membrane) and capsular cells (modified fibroblasts, no basement membrane).
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  • 39
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: This study is concerned with the finding of cytoplasmic annulate lamellae in normally developing avian somatic tissues. Annulate lamellae were observed in hepatic parenchymal and pancreatic beta cells of the chick embryo on days five and eleven, respectively, of egg incubation. The presence of this cytoplasmic membrane system in normal embryonic tissues supports the view that annulate lamellae may represent normally occurring, transitory organelles common to virtually all cells during early embryonic differentiation.
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  • 40
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    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 140 (1974), S. 181-190 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: It is generally accepted that in the kidney insulin is metabolized in the proximal tubule, but whether in the convoluted segment, the straight segment, or both has not been established. By means of autoradiography counting of radioactivity, and interrupted flow techniques, the following observations have been made. 131I-labelled porcine insulin is metabolized exclusively in the convoluted segment of the proximal tubule. Although the glomerular filtrate is the major source of insulin supply to the renal epithelia, the peritubular capillary plexuses provide as much as 30% or more of the total insulin delivered to the renal epithelia. The epithelium of the convoluted segment is capable of sequestering 131I-insulin from the peritubular capillary plexuses, a phenomenon which has not been established previously.
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  • 41
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 140 (1974), S. 191-199 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Bronchiolar neuro-epithelial bodies in neonatal mice were studied by light and electron microscopy. These bodies occurred in thickened areas of the epithelium, and consisted of groups of specialized, non-ciliated columnar epithelial cells with many cytoplasmic granules. These cells were usually closely parallel to one another and had elongated nuclei containing conspicuous peripheral chromatin condensations. These cells were associated with intra-epithelial axons.With electron microscopy, the non-myelinated axon under the neuro-epithelial body was observed to penetrate the basal lamina and enter the epithelial layer. After penetration, the intra-epithelial axon containing numerous mitochondria lost its Schwann cell sheath, became enlarged, and ramified among the epithelial cells.These innervated neuro-epithelial bodies probably function as sensory receptors in the bronchioles.
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  • 42
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Light and electron microscope examination of gastro-intestinal epithelia in the adult mouse revealed the widespread presence of a cell type characterized by deep surface invaginations or “caveolae” and, accordingly, called “caveolated cell.”The caveolated cells are scattered within the epithelia of stomach, small and large intestine; they have a narrow apex bordering the lumen and a wide base in contact with the basement membrane. In the light microscope, they display microvilli longer than in nearby cells; the cytoplasm is usually pale and contains an apical group of parallel fibrils, next to which are minute light spaces which may correspond to the caveolae. In the electron microscope, each fibril is found to be composed of a bundle of straight filaments, extending from the core of a microvillus down into the deeper portion of the supranuclear region; microtubules are often associated with these filaments. Filaments of a different type are arranged in bundles which go from desmosome to desmosome around the apical region of the cell. The caveolae are long and tortuous channels opening at the cell surface between the microvilli and extending deep into the cytoplasm. From the walls of caveolae, polyp-like structures project into the lumen. The heads of the polyps are believed to be released into this lumen where they appear as small spheres. These in turn may come out of the caveolae to appear between and next to the microvilli.Caveolated cells are not numerous, e.g., they make up less than 1% of the epithelial cells in the crypts of descending colon. They may be found in the intestinal crypts among poorly differentiated cells, and at the surface of stomach and intestine among fully differentiated cells. They appear to undergo renewal, but since they have not been seen in mitosis, they probably arise from the differentiation of some other epithelial cells.
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  • 43
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Morphological changes in the acrosomic system and nuclei of developing spermatids were evaluated as a basis for classifying the stages of the cycle of the seminiferous epithelium in the bovine testis. Light microscopic examination of periodic acid-Schiff-stained testicular tissue permitted identification of 14 steps of spermatid development (spermiogenesis). The first 12 steps in this sequence were utilized as the major criterion to divide the cycle of the seminiferous epithelium into 12 distinct stages. Following this, the pattern of germ cell differentiation was investigated by counting the number of germ cells at each stage of the cycle. Based on cell counts, type A spermatogonia divided primarily during stages VII-VIII and IX-X of the cycle. Some type A cells divided again at the end of stage XII to produce intermediate spermatogonia, while others apparently remained “dormant” until the following cycle. At the end of stage IV, intermediate spermatogonia divided to produce type B1 spermatogonia which in turn divided at the end of stage V to produce type B2 spermatogonia. Primary spermatocytes appeared during stage VIII and divided late in stage XI of the following cycle to form secondary spermatocytes. These divided to form young spermatids at the end of stage XII. It was concluded that changes in the acrosomic system and nuclear morphology of developing spermatids provide useful criteria for dividing the cycle of the seminiferous epithelium into stages as well as investigating the pattern of germ cell development during spermatogenesis in the bovine testis.
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  • 44
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Vinblastine sulfate was given to adult rats by two tail-vein injections. After a total treatment time of five hours, kidney cortex was fixed and prepared for examination by routine transmission electron microscopy. Cells of proximal convoluted tubules from treated animals were found to contain focal aggregates of smooth endoplasmic reticulum. Such aggregates were not normally present in cells of control animals. The smooth membranes of these aggregates bear some resemblance to phenobarbital-induced proliferations of smooth endoplasmic reticulum described in liver cells by many previous investigators, and the suggestion is made that the aggregates described here may reflect a vinblastine-induced increase within proximal tubule cells of enzymes which function in drug metabolism. That molecules of vinblastine actually entered proximal tubule cells was evidenced by the fact that cytoplasmic microtubules were greatly reduced in number and paracrystals of microtubular protein were occasionally observed.
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  • 45
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Horseradish peroxidase was used to explore electron microscopically the uptake and transport of protein by the rat visceral yolk sac at 2 minutes, 6 hours, and 12 hours following a single intravenous injection into pregnant rats on day 12 and day 21.5 of gestation.On both days, the visceral endoderm absorbed peroxidase via micropinocytosis at 2 min postinjection, but not at the 6 and 12 hr intervals. At the latter two postinjection intervals on day 12, peroxidase was localized mainly at two sites, i.e., within intraepithelial supranuclear storage vacuoles, and within the vitelline endothelium deep to the visceral endoderm. On day 21.5 at 6 and 12 hr postinjection, peroxidase was localized in supranuclear storage vacuoles, though most of it was within tubular structures and small vacuoles in the paranuclear and infranuclear cytoplasm of the endoderm. Many dense vacuoles were in close anatomical relationship with the basal cell membrane. Deep to the endoderm a few macrophages were actively engulfing peroxidase, but reaction product was rarely found in the fenestrated vitelline endothelium.The results presented differ from the previous physiological and anatomical transport studies of the visceral yolk sac in that protein (peroxidase) transport was observed deep to the endoderm during both mid- and late gestation.
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  • 46
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Perivertebral cervical connective tissue was taken from chick embryos of incubation ages from 72 hours through hatching and from 4, 8, 12, and 16 week old chicks. Preparations for electron microscopy were routine except for en bloc staining with 5% aqueous uranyl acetate. Collagenase digestions of thin sections confirmed the presence of tropocollagen in banded extracellular fibrils.Banding becomes demonstrable in fibrils at about seven days but repeating units cannot be measured. Close to connective tissue cells the banded material is present in wide sheets. Partially banded fibrils (250 Å wide) physically related to microfibrils are present in acellular regions. Growth in fibril diameter is slow through the second week (up to 300 Å) but increases nearly 200 Å on days 14 and 15. Fibrils larger than 500 Å resist uranium and lead staining following the period of accelerated growth. Smaller fibrils (〈 500 Å) continue to stain well. A basic banding pattern of measurable periodicity is established by the eighth day. This consists of a major doublet, two minor doublets, and two singlets. The intraperiod distance does not change significantly with growth (510 Å average). Additional bands near the first minor doublet and singlets of the basic pattern are first clearly demonstrable at 14 and 15 days. Ambiguities in banding and period length are believed to be due to plane of section, interference with detail by other fibrils and flaky amorphous material or possibly to differential shrinkage along the length of a single fibril.
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  • 47
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    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 140 (1974), S. 263-279 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Adult male rats received 5 mg methotrexate daily and were sacrificed 1, 1.5, 2, 2.5 and 3 days after the beginning of the treatment. Other groups received 9,000 rads of abdominal x-radiation and were sacrificed 1, 2 and 3 days later. Histological samples were taken from five regions of the small intestine and processed for light microscopic examination. Average area occupied by the crypts and the villi respectively, was measured per unit length of histological section. A few animals received 3H-thymidine an hour before the methotrexate treatment or irradiation; the histological samples were processed for radioautography.Significant mitotic activity was absent throughout the experiments. During the first 1.5 days, mainly the crypts diminished. Radioautography revealed that migration of crypt cells to the villi continued during this time. During the second and third days, the villi also showed marked diminution, and cell migration became irregular. In general, the histometric data were similar after methotrexate and irradiation. Epithelial denudation started in terminal ileum on the third day after methotrexate. The epithelium was much reduced but not yet denuding at this time in the irradiated animals.Methotrexate inhibition of DNA and RNA synthesis was assumed to be associated, respectively, with mitotic inhibition and with a decline of protein synthesis which manifested itself in villus diminution. Survival of epithelial cells varied presumably according to the amount of RNA pool and was longest in cells being in the S-phase at the onset of the treatment. The similarity of the data after irradiation implied a similar sequence of events.
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  • 48
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Electron microscopy of superior cervical ganglia of the mouse shows both pre- and postganglionic elements impinging upon the soma of principal neurons. The preganglionic cholinergic axon terminals are estimated to cover about 0.7% of the total surface area of the neuronal soma and are characterized by dense packing of synaptic vesicles which remain unchanged after the administration of 5-hydroxydopamine. Postganglionic elements are estimated to cover about 1.8% of the total surface of the neuronal soma. In many cases they contain small granular vesicles (with or without agranular reticulum), and are considered to be represented in part by vesiculated segments of the dendrite and in part by recurrent axon collaterals of the principal neuron. These postganglionic elements usually make puncta adhaerentes, but occasionally an efferent synapse, on the soma of principal neurons in the ganglion. Evidence is presented which suggests that the soma, in turn, is capable of influencing the perisomal, postganglionic elements through a somatic efferent synapse.
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  • 49
    Electronic Resource
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    New York, NY [u.a.] : Wiley-Blackwell
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 50
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    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 140 (1974), S. 299-337 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Hepatic glycogen patterns are described for rats adapted to a precisely controlled feeding schedule and ad libitum fed rats. Liver samples were processed for biochemical and histochemical glycogen analysis at precise intervals following a 22 hour fast and a 2 hour meal. Histochemical determination of glycogen (PAS) after freeze substitution showed lobular patterns of hepatic glycogen which correlate with chemically determined glycogen levels and nutritional states of the rats. After 22 hour fasting, hepatocytes from rats with low glycogen levels (〈 0.09%) exhibited no significant staining. In control fed rats, feeding caused glycogen deposition throughout the lobule but in greatest concentration centrilobularly throughout the early phases of glycogen accumulation. As glycogen deposition continued, periportal lobular patterns were observed in rats with high glycogen levels (〉 5%). Glycogen depletion reduced glycogen staining in cells throughout the lobule, but centrilobular patterns prevailed until late in depletion when periportal patterns appeared. Ad libitum-fed rats showed similar glycogen patterns except maximum deposition was characterized by centrilobular or even lobular distribution of glycogen, and periportal patterns of glycogen were seen only rarely in extreme fasted rats. Differences in lobular patterns between ad libitum and control fed rats is apparently related to lower maximum hepatic glycogen levels reached by ad libitum-fed animals.
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  • 51
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    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 140 (1974), S. 339-347 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Formation of the myelin sheath in peripheral nerve of the newborn rat is compared with its formation in postnatal cerebral white matter. The unmyelinated central axon is bare and myelination begins by the spiral wrapping of an oligodendrocytic process around the axon. The paired membranes of this process fuse on their inside surfaces, lengthen, and spiral around the axon to make a loose sheath of major dense lines. Compact myelin results after fusion of the outside surfaces to form the intraperiod line. Cytoplasm is sparse in developing central myelin, usually being restricted to inner and outer tongues.Unmyelinated peripheral axons are enclosed within a mesaxon formed by the invagination and fusion of the outside surfaces of the Schwann cell plasma membranes. Loose myelin is produced by lengthening and spiralling of the mesaxon (intraperiod line) around the axon. As Schwann cell cytoplasm is extruded from between the spirals, the major dense line forms and compact myelin results. Trapped cytoplasm, a characteristic of developing peripheral myelin, is found in the internodal compact myelin sheath as the inner and outer collars and the Schmidt-Lanterman clefts.
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  • 52
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Reactions for hydrolytic enzymes such as aminopeptidase, β-glucuronidase, N-acetyl-β-glucosaminidase, arylsulfatase and non-specific esterases indicated various degrees of activity within the chondrocytes of the young mandibular condyle. Most of the reaction products of the above enzymes appeared as discrete granules, which might indicate a lysosomal origin. The most intense activity of these enzymes was observed within chondroblasts and premineralizing hypertrophic chondrocytes. However, chondrocytes within the mineralizing zone also appeared synthetically active. The latter cells, as well as those at the adjacent ossification front, revealed some activity by a majority of the enzymes tested. This could indicate that some metabolic functions, although reduced in degree, continue in the cells of these mineralizing zones of endochondral ossification.Matrical reactions, with the exception of arylsulfatase and aminopeptidase, were essentially negative. The positive reactions for the latter enzymes might be an indication of their involvement in the process of extracellular mineralization.
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  • 53
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The response of the kidneys of 237 adult newts [Notophthalmus (Diemictylus) viridescens] to partial nephrectomy (15 to 30% of right kidney removed) and sub-total nephrectomy (70 to 90%) was studied histologically and autoradiographically to determine their regenerative potential. The response involved both hypertrophy and hyperplasia as indicated by increases in 3H-thymidine labelled nuclei and also 3H-leucine incorporation by the remaining cells of the kidney. Leucine incorporation increased within 24 hours and continued to increase until 5 days after partial nephrectomy (17% increase over control level) or 15 days after sub-total nephrectomy (36% increase). The number of thymidine labelled nuclei, however, did not increase for the first 5 days and then continued to increase up to 10 days after partial nephrectomy (to 3X control level) and 20 days after sub-total nephrectomy (to 5X control level).An accumulation of cells appeared on the cut surface of the kidney by 15 to 20 days after nephrectomy. It consisted of modified epithelial cells from the tubules and was characterized by marked basophilia. The number of 3H-thymidine labelled nuclei in the accumulation increased about 10 to 20 times over control levels at its peak on days 12 to 15; 3H-leucine incorporation doubled at its peak on days 10 to 15. Nevertheless, after day 20 the cell accumulation decreased in size due to cell resorption or sloughing or both; it had disappeared by day 50 with no new tissue resulting. The newt kidney does not appear to exhibit any regenerative potential and, therefore, it is similar to mammalian kidneys in this respect.
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  • 54
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Incubation of human oral mucosa in physiological solutions containing proteolytic enzymes permits separation of the preparation into its epithelial and connective tissue components. Trypsin, collagenase and elastase were utilized to effect epithelium-connective tissue separation. Elastase was the most suitable in that a reliable separation of the epithelium from the connective tissue occurred at the lamina lucida (the electron-lucent zone between the basal cell and basal lamina) with only minimal alteration of the epithelium. The most common change observed in separated epithelium was the formation of cytoplasmic protrusions or blebs on the inferior surface of the epithelial basal cell. Bleb formation was quite extensive when preparations were incubated one to two hours beyond the point where the epithelium could be separated from the connective tissue. With prolonged incubations inferior aspects of epithelial basal cells demonstrated the formation of an entirely new cytoplasmic front apparently resulting from fusion of membranes and subsequent confluence of the cytoplasm contained within the blebs. Individual hemidesmosomes or small lengths of the original inferior epithelial basal cell membrane became enclosed in membrane-bound vacuoles within the cytoplasm of the epithelial basal cell. These vacuoles were shown to have been interiorized by the absence of a ruthenium red reaction product within the vacuolar spaces. Bleb formation was shown to be strictly enzyme-induced since intact specimens demonstrated extensive basal cell blebbing following prolonged incubation. Occasional desmosomes were broken and the component halves interiorized in membrane-bound vacuoles within the cell cytoplasm. Alterations observed in epithelial basal cells as a consequence of exposure to exogenous proteolytic enzymes mimic alterations observed in many disease processes and during certain stages of development.
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  • 55
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The development of the fetal membranes of the North African jerboa (Jaculus) and the North American jumping mouse (Zapus) were examined by light microscopy, and the interhemal membrane of Zapus was studied by electron microscopy. Early stages of Jaculus show implantation to be antimesometrial with the embryonic disc oriented mesometrially. Amniogenesis is by folding and there is a distinct epamnionic cavity. Yolk sac inversion is complete, but the disappearance of the parietal segment occurs relatively late, during the early fetal period. Those early stages of Zapus which were available indicated a close similarity to Jaculus. Both Jaculus and Zapus are unusual in the manner of development and composition of the chorio-allantoic placenta. Development of cytotrophoblast and syncytiotrophoblast is arrested early and these layers eventually disappear. Trophoblastic giant cells migrate into the allantoic mesenchyme to form the maternal blood channels of the labyrinth. In Jaculus, a complex interdigitation exists between yolk sac villi and arterial channels bringing maternal blood to the labyrinth. This relationship is much less intimate and extensive in Zapus. Electron microscopic examination of the interhemal membrane of Zapus shows it to be hemomonochorial, its only trophoblastic element being the giant cell cytoplasm. Thus, the Zapus placenta is to date one of very few hemochorial placentas known to lack trophoblastic syncytium in its interhemal membrane. Comparison of the total development and structure of the fetal membranes in these two genera with that of other rodents indicates that the membranes of the Dipodoidea, like the Geomyoidea, are intermediate in type between those of the Sciuromorpha and Myomorpha.
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  • 56
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The chorioallantoic placenta from six crabeater seals (Lobodon carcinophagus) with fetuses from 15-180 mm crown rump length (CRL), and two leopard seals (Hydrurga leptonyx) with fetuses 76 and 86 mm CRL was lobulated, zonary, labyrinthine and endotheliochorial. The fine structure of the placenta was essentially similar in both species. Maternal capillaries of the labyrinth had attenuated endothelial cells unlike the fissiped carnivores. They were surrounded by an outer syncytiotrophoblast, incomplete inner cytotrophoblast, and a core of mesenchymal tissue containing fetal vessels. In general, the cytotrophoblastic cells were less electron-opaque than the syncytium; the former possessed abundant free ribosomes, while the latter had many nuclei, mitochondria, and numerous strands of rough endoplasmic reticulum. Mitotic figures were observed only in the cytotrophoblast. Plasma membranes between the trophoblastic layers had interdigitating processes which showed many desmosomes along the intercellular spaces, whereas membranes surrounding the maternal capillaries were usually smooth. In the limb-bud stage embryo, the syncytiotrophoblast had thick and thin areas which became progressively attenuated in older fetuses. Instances of intratrophoblastic fetal capillaries were observed in seals with fetuses of 40 mm CRL and older, with consequent greatly thinned placental barriers. By Perl's reactions, Turnbull's method, and electron microscopy, rows of granular bodies positive for iron were demonstrated along the basement membrane of the trophoblastic cells and in the mesenchymal cells of the crabeater seals, but not the leopard seals. Furthermore, it is suggested that the deposits of granular bodies show the sites of iron storage in the placentas. In the limb-bud stage embryo the hematome borders and isolated pouches of the central hematome were observed. The central hematome was antimesometrial. The hematomes were lined by columnar cytotrophoblastic cells which phagocytized extravasated maternal blood and absorbed histiotrophic material.
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  • 57
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 141 (1974), S. 297-297 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 58
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Cytochalasin-B (CB) induces cells to contract. This contraction is biphasic. The rapid response peaks in 30 minutes and is followed by a slower contraction that leads to the “arborized” configuration. If fully arborized cells are removed from CB and exposed to colcimide they are induced to form twisting, birefringent bands. These bands consist of massive numbers of 100 Å filaments.
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  • 59
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 60
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: This study is concerned with the passage of carbon particles through the sinusoidal lining cells of bone marrow and embryonic liver of the rat. A carbon suspension (Pelikan C11/1431A, Günther Wagner, Hanover) diluted 1:1 with double strength Tyrode solution, was administered through the aorta for the bone marrow studies and through the umbilical vein for observations on the embryonic liver. The carbon particles have a diameter ranging from 220 to 380 Å with a mean diameter of 280 Å. Within three minutes after the injection, the particulate was present in the extravascular spaces. Neither the sinusoidal walls of the bone marrow nor of the embryonic rat liver prior to 16 days gestation have preformed apertures. In both cases, the carbon particles enter the extravascular space through fenestrae with diaphragms. No carbon particles occur in the junctional spaces between the lining cells. The temporary pores caused by diapedetic blood cells maintain a tight seal and no particulate was observed leaving the vascular space at these sites. At 17 days of gestation, open gaps develop in the endothelial lining of the embryonic rat liver and particulate material leaves the vascular lumen through these openings. The presence of bristle-coated vesicles containing particulate material at the abluminal side of the lining cells is interpreted as a retrograde uptake by these phagocytic cells rather than as evidence for vesicular transmural transport.
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  • 61
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    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 141 (1974), S. 303-315 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The purpose of this study was to determine the developmental interrelationships existing between the lobes of the hypophysis and the prechordal mesoderm in the chick embryo.Using glass needles, operations were performed in ovo on embryos of three to 13 somites. The operative series involved extirpations of the prospective area or precursors of: (1) anterior lobe alone; (2) posterior lobe alone; (3) posterior lobe and the prechordal mesoderm together; and (4) anterior and posterior lobe precursors and the intervening mesoderm.The results of these experiments indicate that there is a mesodermal-neural sequence in the inductive process which leads to the development of the anterior lobe. Prechordal mesoderm induces the formation of Rathke's pouch. The latter is then influenced to differentiate through a vascular supply arising from the pial plexus of the infundibular region. Contact of the epithelial and neural rudiments of the hypophysis is not necessary.
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  • 63
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Full thickness holes through rabbit ears are filled from their margins by the regeneration of missing tissue, including the ear's cartilaginous sheet. However, no regeneration of ear tissue occurs if the cartilaginous sheet is removed. If a second sheet of cartilage is implanted into the ear, only one layer of cartilage differentiates in the regenerate. Therefore, although the original cartilaginous sheet is necessary for chondrogenesis in the regenerate, it does not dictate morphogenetic information to the blastema.
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  • 64
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 65
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 141 (1974), S. 459-459 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 66
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Antibody specific for Limulus paramyosin stains the A bands of Lethocerus flight muscle sarcomeres. SDS-polyacrylamide gels of both Limulus telson and Lethocerus flight myofibrillar preparations show bands with mobility similar to that of purified Limulus paramyosin.
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  • 67
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The columnar cells, i.e., the cells which contain neither mucous globules, nor entero-endocrine granules, nor Paneth type secretion, were investigated independently of other cells in duodenum, jejunum and ileum using light and electron microscopy as well as radioautography in mice sacrificed at various times after single injection or continuous infusion of 3H-thymidine.The columnar cells exhibit local differences allowing their classification into four sub-groups: (a) The crypt-base columnar cells are immature proliferative cells occupying the nine lowest cell positions of the crypt on the average. (b) The mid-crypt columnar cells occupy the next positions up to 19 in ileum and 27 elsewhere; they proliferate and show features gradually changing from undifferentiated ones near the base to partially differentiated ones higher up. (c) The crypt-top columnar cells occupy the rest of the crypt; they do not divide but they continue to differentiate. (d) Finally, the villus columnar cells are fully differentiated absorptive cells.Cryp-base and mid-crypt columnar cells take up 3H-thymidine label prior to division. With time after a 3H-thymidine injection, the intensity of their labeling decreases, while heavily labeled columnar cells appear in crypt-top by six hours and on the villus by 12 and more hours. Hence, columnar cells migrate. The migration is associated with gradual differentiation from the immature crypt-base columnar cells to the mature villus columnar cells. The latter eventually reach the villus tips where they drop into the lumen.The columnar cells constitute a large majority of the epithelial cells (95, 94 and 89% in duodenum, jejunum and ileum, respectively). Hence, they are likely to play a key role in the renewal of the epithelium in the three regions of the small intestine. The turnover time of columnar cells estimated from results of continuous 3H-thymidine infusion is 3.3 days in duodenum and 3.4 days in jejunum.Evidence from turnover time data indicates that the mitoses of columnar cells produce more cells than required for their own renewal. Presumably some of the mitoses give rise to cells of a type other than columnar.
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  • 68
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 141 (1974), S. 481-501 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The mucous cell population of duodenum, jejunum and ileum was investigated in the light and electron microscopes with the help of radioautography in mice sacrificed at various times after single injection or continuous infusion of 3H-thymidine.Mucous cells are characterized by globules of mucus and by dilated cisternae of rough endoplasmic reticulum. Two subgroups of mucous cells, one called common and the other granular, may be identified. The granular mucous cells differ from the common ones by the presence of small dense granules embedded within the mucous globules. Each subgroup is further divided into immature oligomucous cells containing few mucous globules, and mature goblet cells with a large accumulation of mucous globules.Common and granular oligomucous cells are found exclusively in the crypt, mainly within the lower mid-crypt, whereas the corresponding two types of goblet cells are present in the upper part of the crypts and in the lower part of the villi. Only common mucous cells are observed in the upper part of the villi.The two types of oligomucous cells, but not goblet cells, have the ability to take up 3H-thymidine and divide. Electron microscopic radioautography demonstrates that, as oligomucous cells migrate upwards, they transform into goblet cells. The latter then migrate to the villus epithelium.In the case of granular mucous cells, this migration is associated with a gradual loss of the characteristic dense granules, so that the granular goblet cells reaching the upper part of the villi become common goblet cells. The goblet cells in the villus epithelium, regardless of their origin, ascend towards the villus tips where they are lost through the extrusion zones.The turnover time of common mucous cells is about three days, as for columnar cells; and that of granular mucous cells, somewhat shorter. In both cases, the divisions of oligomucous cells account only for the production of about half the mucous cells present. Hence, the other half must be derived from precursors other than oligomucous cells. Since a few crypt-base columnar cells contain the odd mucous globule, they are suspected of being the precursors of the two types of oligomucous cells and, through them, of the entire mucous cell population.