ISSN:
1432-0878
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Summary The terminals of the centrifugal fibers to the pigeon retina have been identified and studied by electron microscopy. These endings are found most commonly along the outer margin of the inner plexiform layer and between the lowermost cells of the inner nuclear layer. They are characterized by a tight aggregation of synaptic vesicles within the ending, which gives the terminals an over-all dense appearance. The majority of the terminals appear to be in contact with the basal portions of amacrine cells, and at presumed points of synaptic contact both pre- and postsynaptic membranes show distinctive thickenings. Three days after destruction of the isthmo-optic nucleus, these endings show characteristic degenerative changes. There is a striking decrease in number of synaptic vesicles, with a corresponding proliferation of neurofilaments in the ending. The synaptic vesicles that remain are clustered close to the synaptic membrane densities. Occasionally, centrifugal terminals are found at a much deeper level in the inner nuclear layer, and these terminals make a clear axosomatic contact with cells distinctly different in appearance from the more common amacrines. It is tentatively suggested that these cells are Cajal's association amacrines, whereas the more commonly observed amacrines which the centrifugal fiber terminals contact basally are the ordinary amacrines.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00339827
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