Displaced amacrine and ganglion cells in the newt retina.

The inner nuclear layer and ganglion cell layer of the newt retina contain taurine- and GABA-accumulating cells which are located immediately adjacent to the inner plexiform layer. Transport studies with horseradish peroxidase (HRP) indicate the presence of displaced ganglion cells within the inner nuclear layer of the retina. These are more numerous at the periphery of the retina and constitute about 2.5% of the retinal ganglion cells. Autoradiography, combined with HRP-transport studies, indicate that the taurine-accumulating cells in the ganglion cell layer of the newt retina are not 'true' ganglion cells, but may be displaced amacrine cells. Counts of axons in the optic nerve compared with cell bodies in the ganglion cell layer, demonstrate that only 50-60% of the cells in the ganglion cell layer of the newt retina are truly ganglion cells.