Immunoreactivity for substance P in the Gasserian ganglion, ophthalmic nerve and anterior segment of the rabbit eye.

The distribution of substance P (SP) immunofluorescence was investigated in the Gasserian ganglion, ophthalmic nerve and in the anterior segment of the rabbit eye. About one third of the nerve cell bodies in the Gasserian ganglion exhibited SP immunofluorescence, which was also observed in some nerve fibres of the ophthalmic nerve. In the cornea, some SP-positive nerves were found in the stroma and few of them were also observed in the epithelium. The iris contained numerous nerve fibres with SP immunofluorescence. In the sphincter area such fibres were circular, while the orientation of the SP fibres was radial in the dilator muscle. Both in the iris and in the ciliar body, the largest vessels are surrounded by nerves exhibiting SP immunofluorescence. A few nerve fibres also appeared in the stroma of the ciliary processes.