SENSORY INNERVATION OF CONJUNCTIVAL LYMPH FOLLICLES IN CYNOMOLGUS MONKEYS

Purpose. The importance of neuroregulation of immunoresponsiveness is recognized, but little is known of the innervation of conjunctival fol licles. The access and distribution of nerves in follicles of the palp ebral conjunctiva were therefore studied and those of trigeminal nerve origin distinguished. Methods. Serial sections of follicles were prep ared for light and selected sections for electron microscopy. Intracra nial lesions were made in ophthalmic or both ophthalmic and maxillary nerves several days before fixation in three of the six monkeys used a nd their distribution in follicles identified by induced degeneration. Results. Fine nerves penetrated follicles and terminated on arteriole s, smaller blood vessels, and rarely on high endothelial venules. Othe r nerve branches entered the follicle parenchyma, conducted, and termi nating in fine reticular fibers. Many terminals were identified as aut onomic on morphologic grounds. Few terminals were in direct contact wi th lymphocytes and none were found in germinal centers. Other fibers t erminated in the follicle associated epithelium. A large fraction of t he nerve fibers displayed degenerative changes after lesions and epith elial terminals were no longer present. Conclusions. Nerve distributio n is mostly similar to that found in other lymphoid organs with the ex ception of the epithelial terminals, which are described for the first time in mucosaassociated lymphoid tissue and identified as sensory. B ecause epithelial terminals virtually were absent from the surrounding unspecialized epithelium, it is likely that those of the follicular e pithelium have a specific immune system-related function. They may rep resent a follicle-alerting mechanism to surface stimuli.