Distribution of cholinergic amacrine cells in the retinas of normally pigmented and hypopigmented strains of rat and cat.

We have examined the soma size, number, and distribution of cholinergic amacrine cells in the retinas of albino and pigmented rats and of Siamese and common cats, using an antibody against choline acetyl transferase (ChAT). In the pigmented strains of rat and cat, ChAT-immunoreactive (ChAT-IR) somata were located in both the inner part of the inner nuclear layer (INL) and ganglion cell layer (GCL), and their processes spread in distinct strata of the inner plexiform layer (IPL). The diameters of the somata in the INL and GCL did not differ significantly at any retinal location. Furthermore, soma diameter did not vary with eccentricity, except at the area centralis of the common cat, where ChAT-IR somata in both layers were relatively smaller. In both species, ChAT-IR somata in the GCL outnumbered those in the INL at all retinal locations. Both populations of cells tended to concentrate at the area of peak ganglion cell density and along the visual streak. Additionally, areas of relatively high density extended superiorly from the area of peak density. The same features of morphology and distribution were identifiable in the hypopigmented strains of rat and cat, but the numbers of ChAT-IR cells were consistently higher.