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

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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.