Ovarian development in athymic nude mice. III. The effect of PMSG and oestradiol upon the size and composition of the ovarian follicle population.

The response of 1 month old congenitally athymic nude mice and their phenotypically normal littermates to exogenous pregnant mare serum gonadotrophin (PMSG) and oestradiol-17beta has been tested. An equal increase in the number of growing follicles was detected in both nudes and controls in response to PMSG. A specific increase occurred in the number of unilaminar follicles in the initial growth stages in addition to the increase in the number of multilaminar and vesicular follicles. Oestradiol depressed follicular growth equally in both nudes and controls. The contracted appearance of growing follicles in nudes disappeared under the influence of PMSG and was induced in ovaries of control mice treated with oestradiol. We conclude that the ability of the mouse ovary to respond to exogenous PMSG and the oestradiol is not impaired by congenital athymia as expressed in the nude genotype. The data suggest that the retardation of follicular growth already reported in 1 month old nudes arises from a deficiency of gonadotrophin.