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  • 1
    Electronic Resource
    Electronic Resource
    Cytochemical correlates of structural sexual dimorphism in glandular tissues of the mouse (1975)
    Springer
    Histochemistry and cell biology 44 (1975), S. 225-244 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The parietal epithelium of Bowman's capsule has been analyzed by enzyme cytochemistry in kidneys of mice (C57BL/6J) from birth to 50 days of age. There is a greater tendency for cells in the central portions of the capsular crescent to be cuboidal in postpubertal males than in pre-pubertal mice of either sex or in post-pubertal females where they are generally squamous; moreover, these heightened capsular cells have a distinct microvillous border. Cytochemical procedures were selected which might confirm the morphological suggestion that the cuboidal parietal epithelium possesses an absorptive capacity. The oxidoreductase activity of the mitochondria of the cuboidal cells of this layer is comparable to that of the columnar cells of the proximal convoluted tubule. The cytochrome oxidase activity of the mitochondria in both of these segments of the nephron is intense. This is in sharp contrast to the unreactive mitochondria in the squamous cells of the parietal epithelium. Furthermore, a striking heterogeneity in the degree of cytochrome oxidase activity is evident in the mitochondria of the cuboidal parietal cells as well as in the cells of the proximal tubules. In the former cells, active mitochondria were generally found near microvilli at the apical ends and in the areas of the basal infoldings whereas those in a central position were more frequently unreactive. The brush border of the cuboidal capsular epithelium had prominent alkaline phosphatase and aminopeptidase activities as has previously been observed in other brush borders. Functional capacity corresponding to the morphological and cytochemical specialization of the cuboidal capsular cells was demonstrated by their uptake of horseradish peroxidase. This exogenous protein tracer could be seen in apical vacuoles and phagosomes in the cuboidal parital epithelium. The cytochemical resemblance of the cells of this epithelium to those of the proximal convoluted tubules suggests a similar involvement in resorption and perhaps in active transport. A possible relationship of this differentiation of the capsular epithelium to the proteinuria normal for adult male mice is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00491493
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  • 2
    Electronic Resource
    Electronic Resource
    Cytochemical reaction for cationic proteins as a marker of primary granules during development in chick heterophils (1979)
    Springer
    Histochemistry and cell biology 60 (1979), S. 295-308 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ammoniacal silver reaction (ASR) for cationic proteins was used as a cytochemical marker for the primary or A granules in the cytoplasm of developing heterophils of chick bone marrow. The presence of the electrondense particulate reaction product of silver, which is localized in the fully formed rod-shaped A granules, provides a marker by which the A granules could be distinguished from the B granules of similar size and by which the formation and maturation of both granule types could be followed through the developmental stages. Progressive developmental stages were ascertained on the basis of decreasing cell size, increasing condensation and margination of the chromatin, and the number and morphology of the granules: the stages were divided into promyelocyte, myelocyte, metamyelocyte and heterophil. During the promyelocyte stage, the first appearance of the electron-dense, membrane-bound, spherical granules (0.3–1.0 μm in diameter) is observed in the vicinity of an extensive Golgi complex. They occur in a cytoplasm containing rough-surfaced endoplasmic reticulum, ribosomal clusters, centrioles, mitochondria, microtubules, as well as the membranes, saccules, vesicles and vacuoles of the Golgi complex. These granules are considered as primary but their presence as the only granule type appears very brief. The ASR reaction product is first detected on the surface of these primary granules in late promyelocytes or myelocytes. The secondary or B granule, devoid of reaction for cationic protein at all stages, appears as a condensing vacuole in promyelocytes, but after some A granules are already present. The vacuole contents condense to form the B granules which are 0.1–0.6 μm in diameter, often oval-shaped, and contain a loose filamentous material surrounded by a membrane. Tertiary C granules or lysosomes appear during the myelocyte stage as dense core vesicles (0.1–0.2 μm in diameter) negative for cationic protein.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00500657
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  • 3
    Electronic Resource
    Electronic Resource
    The postnatal development of the sexually dimorphic duct system and of amylase activity in the submandibular glands of mice (1975)
    Springer
    Cell & tissue research 157 (1975), S. 411-422 
    Details
    ISSN: 1432-0878
    Keywords: Submandibular gland (mice) ; Sex-dimorphism ; Amylase ; Development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The submandibular glands of developing and mature Strong A mice were studied by light and electron microscopy. The glands of both sexes show the same cell types during development, but during maturation the glands display a degree of sex-dimorphism. Striated ducts, which differentiate from the larger intralobular ducts present in the neonatal gland, first appear by 5 days of age and reach their mature condition by 20 days of age. Granular convoluted tubule cells, which differentiate from striated duct cells, are first seen at 15 days of age in both sexes. Subsequently, they show a more rapid development in males than in females, and are dimorphically represented by 20 days of age. Intercalated ducts in the neonatal gland contain nongranular and granular cells. With maturation the number of granular cells decreases, apparently due to their conversion into the nongranular type, with their eventual disappearance from the glands of adult males. Their retention in adult females further defines the sexual dimorphism shown by these glands. Amylase activity in gland homogenates is first detectable at 20 days of age in both sexes. During development the male glands show a rapid rise in levels of amylase activity, whereas female glands show a more gradual rise. In mature animals, male glands have higher levels of amylase activity than female glands. The developmental and adult status of amylase activity parallels that of the granular convoluted tubules.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00225529
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  • 4
    Electronic Resource
    Electronic Resource
    Scanning electron microscopic observations of early stages of phagocytosis of E. coli by human neutrophils (1980)
    Springer
    Cell & tissue research 209 (1980), S. 65-70 
    Details
    ISSN: 1432-0878
    Keywords: Phagocytosis ; Human polymorphonuclear leukocytes ; Neutrophils ; E. coli ; Scanning electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Changes in surface morphology, as observed by scanning electron microscopy, appear rapidly when human polymorphonuclear neutrophils (PMN) are challenged with bacteria. Monolayers of PMN adhering to glass were incubated with opsonized E. coli from 5 sec to 10 min, and then fixed and prepared for SEM. As early as 5 sec after phagocytic challenge, E. coli are found in contact with PMN and in the process of engulfment into open cavities formed by lamellipodia. The shape of the mouth of the forming phagocytic vacuole is related to the orientation of bacteria during entry. Bacteria engulfed into early forming phagosomes are surrounded by a large open space between the bacteria and the phagosome wall. As phagocytosis proceeds, the space is reduced and the loose fit around the entering bacteria becomes tight. By 30 sec, bacteria may be completely internalized and by 1 min phagocytized E. coli are packed into bulging PMN. The observations reveal the variability and rapidity of the phagocytic response and confirm the presence of sensitive mechanisms for host defense by PMN.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00219923
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  • 5
    Electronic Resource
    Electronic Resource
    Fine structure of the secretory and non-secretory ameloblasts in the frog. II. Fine structure of the non-secretory ameloblastThis investigation was supported in part by USPHS Research Grant DE 3724. (1978)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 158 (1978), S. 181-197 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The non-secretory ameloblasts present at the enamel-free surfaces of maxillary teeth in the frog Rana pipiens were examined by electron microscopy at different stages of tooth development. Their main fine structural features seem to reflect a transport function. During early tooth development, the non-secretory ameloblasts adjacent to odontoblasts and predentin exhibit extensive lateral surface specializations and numerous cytoplasmic vesicles. During late tooth development, the non-secretory ameloblasts adjacent to mineralizing dentin show numerous cellular junctions, well-developed intercellular channels with numerous interdigitating processes and labyrinthine configurations at their distal surfaces. An intact basal lamina is present between the non-secretory ameloblasts and the dentin surface until the dentin becomes fully mineralized. At this stage the adjacent cells no longer exhibit surface specializations.It is suggested that the non-secretory ameloblasts may participate in the mineralization of adjacent dentin at the enamel-free surfaces. This surface dentin becomes fully mineralized at a later stage of development than the underlying dentin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051580205
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  • 6
    Electronic Resource
    Electronic Resource
    Fine structure of the secretory and nonsecretory ameloblasts in the frog. I. Fine structure of the secretory ameloblastsThis investigation was supported in part by USPHS Research Grant DE3724. (1977)
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 148 (1977), S. 161-193 
    Details
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Amelogenesis in the tooth germs of the frog Rana pipiens was examined by electron microscopy at different stages of tooth development. Cellular changes in secretory ameloblasts during this process showed many basic similarities to those in mammalian amelogenesis.Amelogenesis can be divided into three stages based on histological criteria such as thickness of enamel and the relative position of the tooth germ within the continuous succession of teeth. These stages are early, transitional and late. The fine structure of the enamel-secreting cells reflects the functional role of these ameloblasts as primarily secretory in the early stage, possibly transporting in the late stage and reorganizing between the two functions in the transitional stage. In early amelogenesis the cell exhibits well-developed granular endoplasmic reticulum, Golgi complex, microtubules, dense granules, smooth and coated vesicles, lysosome-like bodies in supranuclear and distal portions of the cell and mitochondria initially concentrated in the basal part of the cell. Numerous autophagic vacuoles are observed concomitant with the loss of some cell organelles at the transitional stage. During late amelogenesis the ameloblasts exhibit numerous vesicles, granules, convoluted cell membranes, junctional complexes and widely distributed mitochondria. Toward the end of amelogenesis, cells become oriented parallel to the enamel surface and the number of organelles is reduced.Amelogenesis in the frog is an extracellular process and mineralization seems to occur simultaneously with matrix formation.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aja.1001480202
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