Effects of p-chlorophenylalanine, amiflamine and melatonin treatment on the ultrastructure of pinealocytes in Sus scrofa.

The effects of p-chlorophenylalanine (pCPA), amiflamine [Fla 336(+)] as well as melatonin (MEL) treatments on the ultrastructure of pinealocytes in immature female pigs were investigated. Treatment of pCPA-tryptophan hydroxylase inhibitor resulted in the presence of numerous membrane-bound bodies type 2, with long, narrow cisterns of endoplasmic reticulum and a large Golgi apparatus. Fla 336(+) selective MAO-A inhibitor influenced the system of dense bodies, mitochondria and lysosomes (increasing their relative volume). Injections of melatonin resulted in the appearance of numerous homogeneous, round, regular shaped structures surrounded by membrane cytoplasmic structures ('granules'). The results indicate that a peculiar system of cytoplasmic dense bodies may be involved in indoleamine secretion in the pig pinealocyte.