THE DISTRIBUTION AND ORIGIN OF SUBSTANCE-P IMMUNOREACTIVE NERVE-FIBERS IN THE RAT CONJUNCTIVA

Indirect immunohistochemistry was used to examine the presence and origin of substance P immunoreactive nerve fibres in the rat conjunctiva. Fluorescent substance P immunoreactive nerve fibres were visualized both in the epithelium and stroma, their number being higher in the stroma where they were associated with blood vessels, the smooth muscle of Müller and the Meibomian glands. Ten to twenty percent of the ganglion cells in the trigeminal ganglion were immunoreactive to substance P, most of them being small in size. Sensory denervation by electrocoagulating the ophthalmic and maxillary branches of the trigeminal nerve caused a complete disappearance of the epithelial fibres and greatly reduced the number of the stromal fibres. These results indicate that the majority of the demonstrated fibres are sensory nerves originating from the trigeminal ganglion. Since sympathectomy had no detectable effect on the number or distribution of substance P immunoreactive nerve fibres, and since some of the fibres remained after sensory denervation it is suggested that at least some of the remaining fibres could be of parasympathetic origin. © 1991.