Immunocytochemical demonstration of serotonergic neurons and processes in the retina and optic nerve of the stingray, Dasyatis sabina.

Neurons and processes in the stingray retina can be stained using PAP immunohistochemistry and an antibody to serotonin, without pharmacological pretreatment. Most of the cell bodies are in the inner nuclear layer while the processes ramify in the inner plexiform layer suggesting the presence of a population of serotonin containing amacrine cells in this species. Scattered immunopositive axons were observed in the optic nerve from the optic chiasm to the optic nerve head.