CELL RENEWAL IN THE OVARIAN FOLLICLES OF THE RAT DURING THE OESTROUS CYCLE AND IN PERSISTENT OESTRUS

The cell renewal rate and mitotic cycles were studied in the ovarian follicles of normal adult females during dioestrus and oestrus as well as in neonatally androgenized females at the age of 8 to 9 months. Incorporation of tritiated thymidine into nuclear DNA was followed using radioautography. The mitotic index was higher during dioestrus than during oestrus, both in the granulosa and in the theca interna cells. The labelling index during dioestrus was 32.4 per cent for the granulosa and 17.7 per cent for the theca, but there was no incorporation of radioactive thymidine during oestrus. The theca externa did not show any DNA synthetizing activity in either of the cyclic phases. A cell cycle was complete during dioestrus within 17 hours in the granulosa and within 31 hours in the theca interna.The polycystic ovaries of the persistent oestrous rats showed practically no mitotic activity. In three out of 12 animals some synthesis of DNA was obtained, and in one of them the labelling index exceeded that of the normal dioestrous rats.