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  • electrooculogram  (2)
  • Cell & Developmental Biology  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Documenta ophthalmologica 72 (1989), S. 83-91 
    ISSN: 1573-2622
    Keywords: chicken ; dark trough ; dopamine ; electrooculogram ; 6-hydroxydopamine ; light peak
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The implication of dopamine in the modulation of the standing potential of the eye was tested in the chicken by an indirect electrooculogram (EOG) method. After a single rapid systemic injection of dopamine, a transient dose-dependent increase in the EOG voltage was observed. EOG recordings during light and dark adaptation were performed after retinal dopamine depletion was induced by intraocular injections of the neurotoxin 6-hydroxydopamine (6-OHDA). The eyes were injected on two successive days with a mixture of 6-OHDA (50 μg), pargyline (a monoamine oxidase inhibitor), and ascorbate added as an antioxidant. Following this treatment EOG recordings were performed 1, 4, and 8 days after the second injection. The electrophysiological changes appeared most spectacular on the fourth day: an important increase in the EOG basal values as well as of the amplitude of the light peak and of the dark trough were observed. Substantial reduction in retinal concentration of dopamine was found in treated retinas. These unexpected electrophysiological data offer additional evidence for the involvement of a catecholamine in the generation of the light peak and the dark trough of the EOG.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-2622
    Keywords: Biosynthesis inhibitors ; chicken ; dopamine ; electrooculogram ; lectroretinogram ; 5-hydroxytryptamine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The involvement of catecholaminergic and indoleaminergic systems in the modulation of the standing potential of the eye was tested in chickens by means of an indirect electrooculography method and direct current electroretinogram recordings. D,L α- monofluoromethyl dopa (MFMD), 50 and 100 nmol), a highly specific inactivator of aromatic L-amino acid decarboxylase, was injected intravitreally. This treatment is known to induce a selective and irreversible blockade of dopamine and 5-hydroxytryptamine biosynthesis. Five hours after drug injection an important increase in the standing potential appeared. The light peak was delayed by about 5 min but its amplitude was unchanged. The return of the standing potential to basal value during maintained illumination was delayed by 5–10 min. The time course of the dark trough was not modified. The intensity-voltage functions were also studied for the various electroretinogram components, 5 hr after MFMD. The voltage of the b-wave was reduced (by 65% with the highest intensity), while the other components were little affected. Substantial reduction in dopamine and 5-hydroxytryptamine concentrations were found in treated retinas. These data, together with previous results, suggest that the standing potential of the chicken eye may be modulated by a balance between catecholamine and indoleamine systems.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 45 (1928), S. 121-185 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: An histological and cytological study of the postembryonic history of the fat-body in Pteronidea ribesi (Scopoli) and Diphadnus appendiculata (Hartig) (both Tenthredinidae) and in Macrocentrus ancylivora Rohwer (Ichneumonidae).The two principal components of the fat-body are the urate-storing excretory cells and the fat-cells.The development and behavior of the excretory cells, especially during the metamorphosis, are described, and in Pteronidea their origin is traced to leucocytes which have become associated with the fat-cells.In the albuminoid inclusions found in the fat-cells two types of substance are distinguished: (a) a basophile material, of nuclear origin, which appears only during the metamorphosis; (b) an acidophile material which appears already during the early larval stages in Macrocentrus, but in Pteronidea is formed only during the metamorphosis and in association with the basophile material. It is thus found that albuminoids formed slowly during larval life may exist from the beginning in the form of acidophile spheres, as occurs in Macrocentrus. But those formed rapidly during the metamorphosis, in all the forms studied, are formed in association with a basophile material derived from the nucleus.The significance of intracellular changes during the metamorphosis is discussed, and the final disposition of the cell inclusions as well as of the fat-cells themselves is described.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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