Retinal distribution of tyrosine hydroxylase immunoreactive cells in two strains of quails Coturnix coturnix japonica.

We have compared the distribution of tyrosine-hydroxylase immunoreactive (TH-I) somata in the retina of two strains of japanese quails, one normally pigmented and one hypopigmented mutant which develops a glaucoma, three months after their hatching. TH-I cells were observed among amacrine and presumptive interplexiform cells in both strains. They were distributed in areas of decreasing densities from an area centralis, located in the central upper retina to the retinal periphery. We have arbitrarilly grouped them in four classes of different densities: A class with 41 cells/mm2 and more, B class (from 31 to 40 c/mm2), C class (from 21 to 30 c/mm2) and D class (20 c/mm2 and less) and drawn isodensity lines. The comparison of cell mean density in each zone showed no major differences between the strains. Conversely, the comparison of the relative retinal surface occupied by each zone demonstrated a significant variation of C and D zones which appeared to be counterbalanced: the C zone being larger and the D zone smaller in pigmented quails compared with mutant quails. The possible involvement of such a TH-I cell distribution and consequently of the dopaminergic system in the development of glaucoma is discussed.