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Neurogenesis of GABAergic cells in the chick retina
Author(s) -
Costa Calaza Karin,
Hokoç Jan Nora,
Gardino Patrı́cia Franca
Publication year - 2000
Publication title -
international journal of developmental neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.761
H-Index - 88
eISSN - 1873-474X
pISSN - 0736-5748
DOI - 10.1016/s0736-5748(00)00055-1
Subject(s) - glutamate decarboxylase , neurogenesis , gabaergic , retina , thymidine , biology , glutamic acid , immunohistochemistry , medicine , endocrinology , microbiology and biotechnology , biochemistry , neuroscience , immunology , amino acid , enzyme , inhibitory postsynaptic potential , in vitro
Two classes of retinal neurons in the chick retina, the horizontal and the amacrine cells, are GABAergic. This study evaluates the neurogenesis of glutamic acid decarboxylase immunoreactive cells in the chick retina. Twenty‐five μCi [ 3 H]thymidine was injected into eggs of 2–10 days and the embryos were sacrificed at embryonic day 18 (E18). Glutamic acid decarboxylase immunohistochemistry was revealed by avidin–biotin complex method followed by autoradiography of thymidine. We used the cumulative method for counting autoradiographic grains. At E3, 10% of the amacrine cells were thymidine negative/glutamic acid decarboxylase positive and this rate remained constant until E6. From E6 to E8 about 80% of the amacrine cells were thymidine negative/glutamic acid decarboxylase positive. At E9, 100% of these neurons had been generated. On the other hand, at E3 only 1.5% of the horizontal cells had been generated (thymidine negative/glutamic acid decarboxylase positive) while at E6 this number increased to 10%. From E6 to E9 the neurogenesis pattern was similar to that found for amacrine cells. Our data show that the great majority (80%) of glutamic acid decarboxylase positive amacrine and horizontal cells proliferate between E6 and E9, i.e. the last 3 days of the neurogenesis period. From E3 to E6 only 20% of the glutamic acid decarboxylase positive amacrine and horizontal cells are generated, which suggests that glutamic acid decarboxylase positive cells may require a specific signal at about E6, which triggers their withdrawal from the cell cycle.