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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 183 (1977), S. 491-498 
    ISSN: 1432-0878
    Keywords: Pineal (Mouse) ; Photoperiod ; Pinealocytes ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The mammalian pineal is thought to produce an antigonadotropic principle under conditions of reduced photoperiod, constant darkness or blinding by optic enucleation. A number of previous studies on mammalian pineals have suggested that the dense-cored vesicles present in pinealocytes may represent morphological evidence of secretory activity. In the present study the ultrastructure of pinealocytes was studied in adult Charles River CD-1 mice blinded by optical enucleation. By one month following optic enucleation the mean number of dense-cored vesicles in the cytoplasm of pinealocytes adjacent to pericapillary spaces had significantly decreased by 55% when compared with intact controls, and remained at this low level at two months and six months. A relative increase in the proportion of large agranular vesicles and an increased number of large, irregular vacuoles was observed also in the pinealocytic polar processes of blinded mice. When compared to control mice the pinealocytic Golgi regions appeared to be hypertrophied in blinded mice. The apparent stimulation of pinealocytic organelles coupled with the observed decrease in dense-cored vesicles suggest an increased synthesis and release of secretory product.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Fertile hens eggs were incubated 48 hours. Embryos were removed from the shell and the cervical region from each excised and placed in a balanced salt solution containing 1% trypsin for 40 minutes. Notochords were isolated by microdissection and further incubated in vitro 48 or 72 hours. Following trypsinization, unincubated notochords were rod-shaped and were shown by electron microscopy to be devoid of extracellular materials or contaminating mesenchymal cells. Extracellular materials, ultrastructurally indistinguishable from those in the perinotochordal connective tissue space in vivo, are present on the surfaces of cell clusters at 48 hours of in vitro incubation. Areas of fibrillogenesis, in which microfibrils are separated from the surface of cells by intermittent basement lamina, are common. At 72 hours of in vitro incubation fibrogenic activity is less evident, but occasionally intense concentrations of small and large microfibrils, basement lamina and other extracellular substances are seen adjacent to notochordal cell surfaces. These observations are of special interest in light of the known role of the notochord in embryonic induction and recent demonstrations that surface-associated substances (specifically collagen) are necessary for normal cytodifferentiation.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Adult male mice were exposed to either alternating illumination or constant illumination for 70 days. Light and dark pinealocytes were compared as to distribution within the gland and ultrastructure. Quantitative studies with the electron microscope revealed a significant reduction in pinealocyte size and Golgi complex size in constant light treatment, as well as a marked but non-significant reduction in the concentration of lipid droplets and irregular vacuoles. Under constant light treatment the cross-sectional area of pinealocyte pericapillary terminals and the number of granulated vesicles per terminal decreased significantly. A greater number of mitochondria appeared swollen, with rarified matrix and reduced numbers of cristae, with constant light treatment.These results provide ultrastructural correlation with the known reduction of pineal weight, protein synthesis and antigonadotrophic activity that is seen with constant light treatment. The marked decrease in concentration of pinealocyte granulated vesicles in constant light treatment gives morphological support to the theory that these vesicles contain antigonadotrophic secretory material.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 141 (1974), S. 441-446 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: We report here the observation of striated collagen produced by notochordal cells in vitro. Fibrils with collagen-like striations were seen in large intercellular spaces following three days of incubation in vitro. Surprisingly, similar fibrils and large sheets (1,500 Å wide) of collagen showing a 510 Å periodicity were seen in notochordal tissues cultured in the presence of β-aminopropionitrile (BAPN), a known inhibitor of cross-linking in tropocollagen. These observations support the view that the notochord should be considered one of several embryonic epithelial tissues known to secrete collagen.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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