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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 178 (1977), S. 411-419 
    ISSN: 1432-0878
    Keywords: Human placenta ; Lysosomes ; Differentiation of cytotrophoblast ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary An ultrastructural and ultrahistochemical study of first trimester human placentae confirms previous reports that the cytotrophoblastic cells show a spectrum of differentiation, that dissolution of the limiting membrane of the cytotrophoblastic cells occurs and that fragments of free membrane can be found in the syncytiotrophoblast. There is an aggregation of primary lysosomes in the region of approximation of the cytotrophoblast to the syncytiotrophoblast, free lysosomal enzymes are found in the space between the two trophoblastic components, secondary lysosomes have been noted in the vicinity of fragmenting cytotrophoblastic cell membrane and the incorporation of a segment of free membrane into a vesicular structure has been noted. It is suggested that placental lysosomes mediate the dissolution of the cytotrophoblastic cell membranes that is a necessary prerequisite for their full differentiation into syncytiotrophoblast and it is further suggested that one of the principal roles of placental lysosomes is in the structural refashioning of the organ that occurs during the first trimester.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0878
    Keywords: Neurohypophysis ; Neurosecretion ; Neurophysin ; Neurohypophysia hormones ; Electron microscopy ; Autoradiography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Electron-microscope autoradiographs have been prepared from the neural lobes of the pituitary glands of rats which had received intracisternal injections of [35S] cysteine at various times before gland removal. The rate of appearance and disappearance of autoradiographically demonstrable radioactivity in the neural lobe closely paralleled that previously determined, biochemically, for radioactive hormones and neurophysins. Radioactivity was appreciably associated with the undilated parts of neurosecretory axons only during the first few hours after injection of the label. The axonal dilations were subdivided into those in which small vesicles could be seen (“endings”) and those in which no small vesicles could be seen (“swellings”). Radioactivity appeared first in “endings” and then in progressively larger and larger profiles of “swellings”. It appeared that newly arrived granules were found close to the limiting membrane of the nerve swelling and that as time progressed they moved deeper and deeper into the swelling. On the basis of the results, suggestions were made for an anatomical explanation of the readily-releasable pool of hormone which has been demonstrated pharmacologically.
    Type of Medium: Electronic Resource
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