Follicular growth and regression during the 8 days after hypophysectomy in sheep

Abstract

Ewes were hypophysectomized on Day 0 and ovareictomized 1, 2, 4 or 8 days later. There was no effect on hypophysectomy on the overall population of follicles > 0.8 mm in diameter during the time studied. However, the growth of healthy follicles > 2 mm in diameter was prevented by Day 2. Turnover of follicles was very active in the ovaries of hypophysectomized ewes as shown by peaks in the proportion of follicles in early atresia at Day 4 and in advanced atresia at Days 1 and 8. By Day 8, most of the measures of the population of follicles 0.8 to 2 mm in diameter were back to the values of Day 0 ewes. The mitotic index of the granulosa cells of the healthy follicles exhibited a similar patter..