Dopaminergic amacrine cells in the cat retina.

Autoradiographic studies of cat retina showed an accumulation of [3H]dopamine in a subpopulation of amacrine cells whose process ramify in the outermost stratum of the inner plexiform layer. Dendrites of these cells are characterized by numerous varicosities measuring up to 2 micron in diameter which are connected by fine intervaricose segments. The dopaminergic amacrine cells are presynaptic to other labeled cells and to unlabeled amacrine populations but not to bipolar or ganglion cells. [3H]Dopamine-labeled processes provide extensive synaptic input to the somata and lobular appendages of type AII amacrine cells. This relationship suggests that dopaminergic amacrine cells may play an important role in the regulation of rod pathways in the cat retina.