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Postnatal development of tyrosine hydroxylase immunoreactive amacrine cells in the rabbit retina: II. Quantiative analysis
Author(s) -
Casini Giovanni,
Brecha Nicholas C.
Publication year - 1992
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.903260211
Subject(s) - retina , biology , tyrosine hydroxylase , amacrine cell , inner nuclear layer , endocrinology , retinal , dopaminergic , medicine , population , neurogenesis , phenotype , soma , microbiology and biotechnology , dopamine , neuroscience , genetics , biochemistry , demography , sociology , gene
Abstract Tyrosine hydroxylase (TH)‐immunoreactive (IR) amacrine cells of the rabbit retina mature during the first four postnatal weeks, and their cellular development is described in the preceding paper (Casini, G., and N.C. Brecha, J. Comp. Neurol. 326:283–301, 1992). The present investigation is a quantitative analysis of the postnatal development of the TH‐IR amacrine cell population. TH‐IR amacrine cells gradually increase in size from birth (soma area of 44.7 ± 12.4 ± μm 2 , mean ± standard deviation) to adulthood (144.2 ± 28.0 μm 2 ). Cell density slightly increases from postnatal day (PND) O (41.9 ± 9.5 cells/mm 2 ) to PND 6 (47.2 ± 7.2 cells/mm 2 ), then markedly decreases from PND 6 to adulthood (17.8 ± 5.3 cells/mm 2 ) as a consequence of retinal growth. TH‐IR cell number almost doubles from PND O (about 4, 100 cells/retina) to adulthood (about 7,850 cells/retina). The increase in the total number of TH‐IR amacrine cells can be explained by the generation of new TH‐IR cells in the inner nuclear layer, a delay in the expression of the TH phenotype after neurogenesis by cells committed to be dopaminergic, or the acquisition of this dopaminergic phenotype by uncommitted cells. The development of the TH‐IR amacrine cell mosaic was assessed by an evaluation of the distribution of nearest neighbor distances of TH‐IR cells. There is a poor correlation between this distribution and a theoretical nonrandom distribution before PND 12. After this age, the nearest neighbor distance distribution shifts towards a nonrandom distribution, and is similar to that of the TH‐IR amacrine cell population in the adult retina. The establishment of the TH‐IR amacrine cell population mosaic is likely to be achieved through different interacting events, including intrinsic (e.g., genetic) factors, environmental influences, and nonuniform retinal growth. Overall, the population parameters analyzed in the present study approach adult values about the time of eye opening (PND 12) and they reach adult values by PND 26. © 1992 Wiley‐Liss, Inc.