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  • 1
    Electronic Resource
    Electronic Resource
    Taurine in toad brain and blood under different conditions of osmolality: An immunohistochemical study (1993)
    Springer
    Neurochemical research 18 (1993), S. 425-435 
    Details
    ISSN: 1573-6903
    Keywords: Taurine ; osmolality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The concentrations of taurine in blood and brain regions of the toadBufo boreas have been measured. Most of these values are considerably lower than those found in mammals. Using an antibody prepared against conjugated taurine, the distribution of taurine in three brain regions of the toad has been visualized. The possible osmoregulatory functions of taurine have been investigated by making toads hyper- or hypo-osmotic in vivo. Induction of hypoosmolality is accompanied by a massive taurine tide in blood plasma, but has no immediate effects upon the taurine concentrations in the brain areas studied. However, histochemical visualization indicates a marked redistribution of taurine between cellular components and extracellular space of brain tissues. This may indicate that taurine has an osmoregulatory function in brain tissue under hypo-osmotic conditions. Hyperosmolality results in no elevation of the taurine concentration in blood plasma of toads, but rather in a very gradual decline of total plasma taurine content over a prolonged time period. Histochemical studies reveal little change in frontal cortex after 1 hour but deeper staining of many neurons in optic lobe accompanied by greater staining in the extracellular fluid. By 3 hours there is a depletion of taurine from all compartments of cerebral cortex tissues. No evidence of any prolonged direct osmoregulatory role for taurine is indicated under hyperosmotic conditions. A possible indirect osmoregulatory function of taurine is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00967246
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Ultrastructure of the integumental melanophores of the South American lungfish (Lepidosiren paradoxa) and the African lungfish (Protopterus sp.) (1975)
    Springer
    Cell & tissue research 158 (1975), S. 375-389 
    Details
    ISSN: 1432-0878
    Keywords: Skin pigmentation ; Melanocytes ; Melanophores ; Electron microscopy ; Lungfish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The integumental melanophores of two genera of lungfish, Lepidosiren paradoxa and Protopterus sp. were examined by light and electron microscopy. Both species possess both epidermal and dermal melanophores with fine structural characteristics basically similar to those of other vertebrates. The epidermal melanophores of both species are located in the intermediate epidermis, and possess thin perikarya containing round nuclei, and slender dendrites extending into the nearby intercellular spaces. The dermal melanophores occur immediately beneath the basement membrane, and possess flat perikarya and dendrites running horizontally between the collagen fibers of the dermis. The integument of both species does not possess an epidermal melanin unit or a dermal chromatophore unit. As in other vertebrates, each melanophore contains numerous oval, electron-opaque melanosomes, relatively large mitochondria, vacuolar endoplasmic reticula, and groups of RNP particles. Although micro filaments running randomly between other organelles occur regularly, microtubules were not demonstrated. Premelanosomes at various stages of differentiation were best illustrated in the dermal melanophores of Protopterus, and it is concluded from the observation of their fine structure that the morphological development of lungfish melanosomes closely parallels that of higher vertebrates. On the basis of melanophore morphology, Lepidosiren and Protopterus appear to be more closely related to each other than to Neoceratodus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00223834
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Ultrastructure of the integumental melanophores of the Australian lungfish, Neoceratodus forsteri (1975)
    Springer
    Cell & tissue research 158 (1975), S. 363-373 
    Details
    ISSN: 1432-0878
    Keywords: Skin pigmentation ; Melanocytes ; Melanophores ; Lungfish ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The integumental melanophores of Australian lungfish, Neoceratodus forsteri, were examined by light and electron microscopy and found to possess essentially the same structural characteristics observed in other vertebrates. The epidermal melanophores are located in the intermediate epidermis and possess round perikarya and slender dendrites extending into nearby intercellular spaces. The dermal melanophores are found immediately below the basement membrane as well as in the deeper dermis. These cells possess flattened nuclei and dendrites running parallel to the basement membrane. Each melanophore contains numerous oval or elliptical, intensely electron-dense melanosomes, relatively large mitochondria, systems of vacuolar endoplasmic reticulum, groups of free RNP particles, and some microfilaments. Only a few, short microtubules could be demonstrated in the perinuclear cytoplasm of the dermal melanophore, while a relatively large number of late premelanosomes are found both in perikarya and dendritic processes of epidermal melanophores. These premelanosomes exhibit a particulate internal structure in cross section. Both melanosomes and premelanosomes occur singly in the cytoplasm of epidermal cells, thereby confirming the existence of the epidermal melanin unit in the lowest vertebrates thus far examined electron microscopically.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00223833
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    Paper (German National Licenses)
    Fulltext
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