Course of structural changes in the microcirculation of growing and atretic ovarian follicles

Synchronized populations of growing and atretic vesicular follicles were obtained in the ovaries of prepubertal mice by injection of serum gonadotrophin. Light-optical and ultrastructural analysis by morphometric methods revealed definite correlation between the size of the follicles and the degree of their vascularization during growth and atresia. The results suggest that the microcirculation plays the leading role in the initiation of atresia.