Leu-enkephalin immunoreactivity in the pig pineal gland

Leu-enkephalin-pogitive structures in the pig pineal gland were demonstrated immunohistochemically using mouse monoclonal antibody. The pineal glands were obtained from the newborn, 21-day-and 7-month old female pig. The immunopositive nerve fibers were observed in the pineal gland as well as in the epithalamic areas. The leu-enkephalin-immunoreactive nerve fibers (single or forming small bundles) were localized mainly in the proximal part of the pineal and they were scarce in other parts. The localization of the fibers points to a centrals source of this innervation. The study did not show any age-dependent differences in the distribution and density of leu-ekephalin-positive nerve fibers.