Tyrosine hydroxylase immunohistochemistry fails to demonstrate dopaminergic interplexiform cells in the turtle retina.

A number of catecholaminergic, presumably dopaminergic, cells could be observed in the turtle retina, because of their tyrosine hydroxylase immunoreactivity. They were amacrine cells with a pear-shaped soma and dendrites distributed in 3 sublayers within the inner plexiform layer. Neither sclerally directed TH-positive processes nor terminals in the outer plexiform layer were observed, suggesting that dopaminergic interplexiform cells do not exist in the turtle retina.