IMMUNOCYTOCHEMICAL AND ULTRASTRUCTURAL EVALUATION OF THE DISTRIBUTIONOF NERVOUS-TISSUE AND NEUROPEPTIDES IN THE MEIBOMIAN GLAND

Background: The ultrastructure of the meibomian gland, of its innervat ion and the localization of neuropeptides in the glandular tissue of t he guinea pig and humans are incompletely known. Therefore they have b een investigated in the present study. Methods: The ultrastructure of the tissue was examined using standard transmission electron microscop ic techniques. Additional scanning electron microscopy was carried out on rabbit tissue. Antisera against the neuronal marker protein gene p roduct were used to demonstrate the distribution pattern of the nerve fibers. The neuropeptides substance P (SP) and neuropeptide Y (NPY), v asoactive intestinal polypeptide (VIP) and calcitonin gene-related pep tide (CGRP) and the neuronal enzyme tyrosine hydroxylase (TH) were ide ntified by their specific antisera. Results: The glands were found to be composed of arrays of alveoli. The outer cells of the alveoli form a germinal layer. Toward the inside of the alveolus the cells are lade n with a secretory substance. The cells disintegrate as they approach the excretory duct. Nerve fibers from a plexus around the alveoli. The se nerve fibers form synapses a distance to the basal alveolar cells a nd enter the basal lamina of the capillaries. In guinea pigs many nerv e fibers were positive for the neuropeptides SP and NPY and for VIP, a nd fewer for CGRP and TH; in humans only SP and CGRP were demonstrated . Conclusion: Both the density of nerve fibers and the presence of var ious neuropeptides suggest that the stimulation of the meibomian gland is subject to nervous control.