Number and distribution of putative cholinergic neurons in the cat retina.

The number and distribution of putative cholinergic amacrine cells in cat retina was demonstrated by immunocytochemical localization of choline acetyltransferase (ChAT), the synthesizing enzyme for acetylcholine. In whole mount preparations of the cat retina ChAT-immunoreactive neurons were found in the inner nuclear layer (presumably amacrine cells) and in the ganglion cell layer (presumably displaced amacrine cells). The density of ChAT-labelled neurons increased from about 280 cells/mm2 in peripheral retina, to about 2750 cells/mm2 in the central area. There were always more ChAT-positive cells in the ganglion cell layer (50-70%) than in the amacrine cell layer. Two narrow dendritic strata were labelled in the inner plexiform layer.