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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 199 (1989), S. 299-311 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Gonadal differentiation in premetamorphic Bombina orientalis is described and staged. The pattern of events during differentiation in Bombina differs in several respects from that previously described in other anurans. The Bombina gonad initially develops on the ventral surface of the vena cava, where there is no pre-existent somatic genital ridge prior to the arrival of the germ cells. The sexually undifferentiated gonad does not have a distinct cortex and medulla; instead, medullary cells ingress from the mesonephric blastema during sexual differentiation. Formation of a testis or an ovary appears to depend on the ability (or lack of ability) of the medulla to invade the germ cell-containing cortex. In the germ line, sexual differetiation can be recognized by a premeiotic increase in oogonial cell volume.
    Additional Material: 8 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 189 (1986), S. 189-197 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Cells considered to be migratory in the cerebral cortex of adult lizards are ultrastructurally of two types. Nuclei in the first type have highly dispersed chromatin, creating a spongy appearance, whereas in the second type the chromatin is irregularly clumped. Both types of cells are closely associated with processes of radial ependymal glia cells, which perhaps orient their migratory pathways. Cells with spongy chromatin show an increase in cytoplasmic organelles and progressive chromatin condensation as they travel from the ependymal layer to the granular layer. Possibly these cells account for the neuronal increase that takes place in the granular layer during postnatal life. Cells with chromatin clumps are very scarce; ultrastructurally they resemble immature reptilian astroglia cells.
    Additional Material: 8 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 194 (1987), S. 311-322 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The architecture of follicular blood vessels in the ovary of lizards (Anolis equestris and Anolis carolinensis) was studied by standard histology and also after vascular perfusion with an orange silicone-rubber compound or with India ink. The theca of the follicular wall contains a netlike arrangement of anastomosing sinusoids, which increase in size as a follicle grows. An avascular stigma forms in very small, growing follicles when a portion of the follicular wall contacts the ovarian surface epithelium. Blood vessels then invade the theca except in the zone of contact. The diameter of the stigma is about 50% of follicular diameter, regardless of follicular size. Although the stigma of smaller follicles is avascular, that of vitellogenic follicles is hypovascular, i.e., a few vessels radiate into the stigma region. The antiangiogenic process involved in stigma formation may continue as the stigma enlarges. The development pattern of stigma formation found in Anolis is displayed by many other vertebrates.
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  • 4
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: It is known that a number of species in the annelid family Lumbricidae harbor symbiotic microorganisms in the lumen of their nephridia. The purpose of the present paper is the study of the relationship between microbes and epithelial cells lining the metanephridium of two species of Oligochaeta, which show two different patterns of microbial colonization. A new interesting feature, the phagocytosis and intracellular destruction of microorganisms by the nephridial epithelial cells, has been observed in our laboratory for the first time. In Scheroteca savignyi minor, the phagocytic activity takes place in the bladder, the most distal region of the nephridium, next to the nephridiopore, which may prevent the microorganisms from entering the more proximal regions. In Octolasion cyaneum the microbes reach the striated duct, where they live in symbiosis, adhere to the cell's surface, and are engulfed and destroyed by the cells of the middle tubule - the more proximal, neighboring region. The phagocytosis and intracellular degradation of microorganisms probably lead to the massive formation of lamellar bodies, which are observed in these cells and in the neighboring ones.
    Additional Material: 10 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 194 (1987), S. 275-286 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The morphology of cells and the organization of axons were studied in Golgi-Colonnier and toluidine blue stained preparations from the medial cerebral cortex of the lizard Lacerta pityusensis. In the medial cortex, six strata were distinguished between the superficial glial membrane and the ependyma. Strata I and II formed the outer plexiform layer, stratum III formed the cellular layer, and strata IV go VI the inner plexiform layer. The outer plexiform layer contained smooth bipolar neurons; their dendrites were oriented anteroposteriorly and their axons were directed towards the posterior zone of the brain. Five neuronal types were observed in the cellular layer. The spinous pyramidal neurons had well-developed apical dendrites and poorly developed basal ones. Their axons entered the inner plexiform layer and gave off collaterals oriented anteroposteriorly. The small, sparsely spinous pyramidal neurons had poorly developed dendrites and their axons entered the inner plexiform layer. The spinous bitufted neurons had well-developed apical and basal dendritic tufts. Their axons gave off collaterals that reached the outer and inner plexiform layers of both the dorsomedial and dorsal cortices. The sparsely spinous horizontal neurons had dendrites restricted to the outer plexiform layer. Their axons entered the inner plexiform layer. The sparsely spinous, multipolar neurons had their soma close to stratum IV and their axons entered the outer plexiform layer. In stratum V of the inner plexiform layer were large, spiny polymorphic neurons; they had dendrites with long spines, and their axons reached the cellular layer. On the basis of these results, we have subdivided the medial cortex into two subregions: the superficial region, which contains the neurons of the cellular layer and their dendritic domains, and the deep region, strata V and VI, which contains the large, spiny polymorphic neurons. The neurons in the medial cortex of these lizards resembles those in the area dentata of mammals. On this basis, the superficial region may be compared to the dentate gyrus and the deep region to the hilar region of the hippocampus of mammals.
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  • 6
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The secretory nature of the isoproterenol-induced mouse parotid polypeptides C, D, E, F, and G (molecular weights 64,000, 61,000, 51,500, 38,000, and 37,000, respectively) is documented. Polypeptides C, D, E, F, and G, accumulated in response to successive daily stimulations with isoproterenol, were detected in a fraction enriched in hypertrophic parotid acinar cells. These cells, characterized by an increased content of cytoplasmic granules, maintain a secretory responsiveness to isoproterenol, which has been evidenced by light microscopy, enzymatic analysis, and unidimensional SDS-polyacrylamide gel electrophoresis. Thus, a parallelism in the loss and recovery of both secretory granules, α-amylase and polypeptides C, D, E, F, and G, was observed. Moreover, after secretion stimulation, polypeptides C, D, E, F, and G were detected in the fluid collected directly from parotid gland cannulation. Given the secretory character of polypeptides C, D, E, F, and G, mechanisms explaining both their progressive accumulation along the chronic administration of isoproterenol, as well as their progressive disappearance observed after suspending that treatment, are discussed.
    Additional Material: 5 Ill.
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  • 7
    ISSN: 0730-2312
    Keywords: cAMP ; cholera toxin ; CD3 molecules ; CD2 molecules ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: We investigated the action of cholera toxin on the intracellular ionized calcium [Ca2+]i increase induced by anti-CD2 and anti-CD3 monoclonal antibodies in the leukemic human T-cell line Jurkat. Cholera toxin inhibits in a dose-dependent manner these two pathways of human T-lymphocyte activation but with different half maximal inhibition doses (75 ng/ml for CD3, 30 ng/ml for CD2). This effect cannot be accounted for only by the increase in cAMP induced by cholera toxin because forskolin, which raises cellular cyclic adenosine monophosphate (cAMP) to the same levels, induced only a small inhibition of the [Ca2+]i increase in similar conditions. Cholera toxin induced a decrease in the surface expression of the CD3 molecule, suggesting a down-regulation of the CD3 molecules. On the other hand, the expression of CD2 remained unchanged. Cell surface disappearance of the CD3 molecule cannot account for all the inhibitory effects of cholera toxin because CD2 molecule expression was not affected (no modifications in the half maximal binding of anti-CD2 monoclonal antibodies). All together, these results suggest that cholera toxin acts on substrates, possibly G proteins, that could regulate the [Ca2+]i increase induced by anti-CD2 and anti-CD3 mAbs in Jurkat cells. In addition, the present study demonstrated that the rise in cellular cAMP partially inhibits the [Ca2+]i increase induced by anti-CD2 and anti-CD3 mAbs.
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  • 8
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The histology of the ovotestis was studied by light and electron microscopy in two nudibranch gastropod species. While in Hypselodoris tricolor the ovotestis is intimately associated with the digestive gland tissue, the large gonadal mass of Godiva banyulensis is placed freely in the haemocoele. This fact results in great histological differences between both species.As is common among Mollusca, the immature yolk granule in Hypselodoris and Godiva presumably originates from membrane-rich cytoplasmic inclusions, which we have termed dense multivesicular bodies. Such inclusions consist of an outer membrane enclosing membrane remnants and a granular, electron-dense material. These elements are accumulated and mixed in the center of the dense multivesicular body and could be actually transformed into the paracrystalline core of the immature yolk granule, the cortex of which is made up of part of the central accumulation materials that have not spread into the crystal. During vitellogenesis, some mitochondria are subjected to a process of transformation affecting mainly their inner membrane (including mitochondrial cristae) and matrix. However, the conversion of modified mitochondria into yolk precursors, as reported for other gastropod species, could not be determined with absolute certainty on the basis of our observations on static material.The mature yolk granule consists of a central paracrystalline core, similar in structure to that of the immature yolk granule, and a peripheral membranous cortex, which seems to spread centripetally, thus permitting the crystal to grow. The cortical material consumed in synthesizing the central core appears to be restored by addition of degenerative mitochondria to the yolk granule surface.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 128 (1986), S. 501-509 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Purified human blood neutrophils were able to bind radioiodinated murine granulocyte-colony-stimulating factor (G-CSF) in a specific manner. This factor has previously been shown to stimulate functional activities of human and murine neutrophilic granulocytes and to be functionally analogous to human-derived CSFβ. The binding of 125I G-CSF to human neutrophils was competed for equally by unlabeled G-CSF and CSFβ but not by other CSF's. Saturation analysis indicated that human neutrophils displayed about 700-1,500 receptors for G-CSF/CSFβ per cell. Three other agents (N-formyl-methionine-leucine phenylalanine, bacterial lipopolysaccharide, and human CSFα) known to activate neutrophils did not compete directly for G-CSF binding sites but, in preincubation experiments at 37°C, were able to down-modulate the expression of G-CSF receptors on human neutrophils in a dose- and time-dependent manner. This effect was specific since the same agents have been shown elsewhere to up-regulate the expression of other granulocyte surface antigens and other agents were much less effective at down-modulating G-CSF receptors. Since the granulocyte-activating agents increase the sensitivity of human neutrophils to G-CSF/CSFβ and mimic some of the actions of G-CSF on neutrophils, it is suggested that G-CSF receptor down-modulation might be a mechanism whereby these agents activate G-CSF receptors and thereby exert some of their effects.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Gamete Research 13 (1986), S. 159-171 
    ISSN: 0148-7280
    Keywords: nudibranch ; spermiogenesis ; nuclear morphogenesis ; chromatin condensation ; manchette ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: An electron microscope study was carried out on Hypselodoris tricolor spermatids to describe the development of the nuclear morphogenesis and investigate the possible cause(s) of the change in the shape of the spermatid nucleus during spermiogenesis. Three different stages may be distinguished in the course of the nuclear morphogenesis on the basis of the morphology and inner organization of the nucleus. Stage 1 spermatid nuclei are spherical or ovoid in shape and the nucleoplasm finely granular in appearance. Stage 2 nuclei exhibit a disc- or cup-shaped morphology, and the chromatin forms short, thin filaments. During stage 3, a progressive nuclear elongation takes place, accompanied by chromatin rearrangement, first into fibers and then into lamellae, both formations helically oriented. A row of microtubules attached to the nuclear envelope completely surrounds the nucleus. Interestingly, the microtubules always lie parallel to the chromatin fibers adjacent to them. Late stage 3 spermatids show the highest degree of chromatin condensation and lack the manchette at the end of spermiogenesis. Our findings indicate the existence of a clear influence exerted on the chromatin by the manchette microtubules, which appear to be involved in determining the specific pattern of chromatin condensation in Hypselodoris tricolor.
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