An immunohistochemical study on the postnatal changes in the C-terminal flanking peptide of neuropeptide Y (CPON)--positive nerve fibers in pineal gland of the pig.

Postnatal development of innervation of the porcine pineal gland by C-terminal flanking peptide of neuropeptide Y (CPON)-immunoreactive nerve fibers was examined using the immunohistochemical technique. CPON-positive nerve fibers appeared in the pineal gland of the new-born piglets and formed plexus in the capsula and connective tissue septa of the gland. The nerve terminals branched off from the plexus and penetrated into adjacent parenchyma. The number of nerve fibers immunoreactive to CPON in parenchyma is very low in new-born and 20-day-old piglets. In 7-month-old pigs they created a dense network.