Ultrastructure of rat pinealocytes during the last phase of pregnancy.

The numbers of Golgi profiles, dense-core vesicles, vacuoles containing a flocculent material, lysosomes, lipid droplets, 'synaptic' ribbons and microtubular sheaves were counted in the rat pinealocytes in the last 5 days of pregnancy. The numbers of Golgi profiles and dense-core vesicles increase at days 21 and 22, while numbers of LYS and LD increase the day before parturition. On the contrary, the number of VFC decreases in the final day of pregnancy. The results of the present study suggest that the pineal gland may play a subtle role in pregnancy.