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Localization of choline acetyltransferase‐like immunoreactivity in the embryonic chick retina
Author(s) -
Spira Arthur W.,
Millar Thomas J.,
Ishimoto Ichiro,
Epstein Miles L.,
Johnson Carl D.,
Dahl June L.,
Morgan Ian G.
Publication year - 1987
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.902600406
Subject(s) - choline acetyltransferase , inner plexiform layer , inner nuclear layer , biology , retina , synaptogenesis , ganglion cell layer , cholinergic , acetylcholinesterase , amacrine cell , cholinergic neuron , outer plexiform layer , microbiology and biotechnology , embryonic stem cell , anatomy , endocrinology , neuroscience , biochemistry , gene , enzyme
Putative sites of acetylcholine synthesis in the retina of the embryonic and posthatched chick were localized immunohistochemically with antisera to choline acetyltransferase; the resultant choline acetyltransferase‐like immunoreactivity (ChAT‐IR) was compared to demonstrated sites of acetyltransferase (AChE) activity, and changes were followed in localization during development. The results confirmed the early and rapid course of development of the chick's retinal cholinergic system described in previous biochemical and morphological studies. Immunoreactivity was first detected at embryonic day 6.5 in cells close to the retina's vitreal surface. By 8 days it was present in cells in two juxtaposed rows; by the ninth day the two rows were separated and Immunoreactivity was evident in two sublaminae of the inner plexiform layer. On the tenth day distribution was like that in the posthatched chicken, in type I cholinergic cells in the inner nuclear layer and in type II cells in the ganglion cell layer (Millar et al.: Neurosci. Lett. 61:311–316, '85.), and similar to that of most vertebrates. Three days before hatching, a third population of weakly immunoreactive cells (type III cells) appeared within the inner nuclear layer. The onset of localizable ChAT‐IR occurred in amacrine cells and in their processes, before the period of synaptogenesis. Acetylcholinesterase activity was localized at an earlier age than ChAT‐IR, and at all ages was present in more cells. The results obtained support the view that “displaced” cholinergic amacrine cells begin to differentiate at the same time and in the same retinal region as type I cholinergic cells. Separation of the two groups is a consequence of the ramification of processes of amacrine and ganglion cells rather than a result of the secondary migration of cells between layers.