VIP (vasoactive intestinal polypeptide)-like immunoreactive amacrine cells in the retina of the rat

Vasoactive intestinal polypeptide (VIP)-like immunoreactivity was demonstrated in the rat retina, using the peroxidase anti-peroxidase (PAP) method. VIP-like immunoreactivity was observed in the cytoplasm of amacrine cells of the inner nuclear layer (INL) and their varicose processes ramifying in the inner plexiform layer (IPL). VIP-like immunoreactive amacrine cells were present in both central and peripheral retinal regions. In some sections fine ramifications of varicose processes in the IPL could be clearly traced. VIP-like immunoreactivity was detected in both 'stratified' and 'diffuse' amacrine cells. VIP-like immunoreactive amacrine cells were classified into four types.