Abstract

The morphology of the pineal body of a migratory duck, Anas discors was studied by light and transmission electrón microscopy (TEM). This study investigates the functional activity of pinealocytes and their role in the maturation of germ cells during the period between arrival from the north (post-migration) and departure (pre-migration). During the shortest photoperiod in November and December (post-migration), pinealocytes exhibit ultrastructure which suggests maximal intracellular activity: e.g., a well developed rough endoplasmic reticulum and Golgi apparatus, and abundant secretory granules. In contrast, the gonad is in an inactive state. As the time for departure (pre-migration), approaches, and the photoperiod gradually lengthen, cells of the gonad differentiate into secondary spermatocytes and spermatids, concomitantly, intracellular synthesis in pinealocytes was reduced.