THE INFLUENCE OF HYPOPHYSECTOMY AND OF SUBSEQUENT TREATMENT WITH CHORIONIC GONADOTROPHIN ON FOLLICLES OF DIFFERENT SIZE IN THE OVARY OF THE RAT

Abstract

Eight days after hypophysectomy there is an increase in the number of small primordial follicles and a decrease in the number of vesicular follicles. The largest diam. reached by the ovarian follicle in the hypophysectomized animal is subnormal. This is probably due to a slowing-down of the growth rate of the follicles. Since the percentage of atretic follicles did not change, it is unlikely that their avg. "life-time" was seriously affected. Chorionic gonadotrophin produces in the hypophysectomized rat a decrease in the number of ova which develop into primordial follicles per unit of time and probably causes a reduction in the rate of growth during the last stages of follicular development. The latter conclusion is based on data derived from the distribution of atresia over various size-groups, the unchanged percentage of atretic follicles and changes in the numbers of medium-sized and largest follicles. Contrary to evidence obtained in normal animals, chorionic gonadotrophin did not increase atresia in hypophysectomized rats.