Ultrastructure of secretory cells of male accessory sex glands of golden hamster (Mesocricetus auratus) and effect of melatonin.

A systematic study of the fine structure of normal (control) and melatonin-treated accessory sex glands (ASG) of the adult male golden hamster has been carried out. Based on the appearance and the predominance of the different organelles, three categories can be identified. They are: (1) the seminal vesicle and ventral prostate, both with prominent Golgi complexes, conspicuous secretory granules and parallel arrays of granular endoplasmic reticulum with narrow cisternae; (2) the coagulating gland and dorsal prostate with cytoplasm dominated by very distended cisternae of granular endoplasmic reticulum and apical blebbing; (3) the ampullary gland featuring abundance of mitochondria and lipid droplets which discharge their contents by the apocrine mode of secretion. Eight weeks of melatonin injection (50 micrograms/animal), administered at the last phase of the light period, induces structural modification reflecting loss of functional activities or even cell deaths of the ASG secretory cells, thus confirming the suppressive effects of melatonin on reproductive structures of rodents.