Ovarian development in athymic nude mice V. The effects of PMSG upon the numbers and growth of follicles in the early juvenile ovary.

The composition and growth patterns of the ovarian follicle population have been determined in early juvenile athymic nude mice and their phenotypically normal littermates. Nude ovaries contained significantly more primordial follicles and fewer trilaminar follicles at 10 days of age. The rate of growth of the oocyte nucleolus was significantly less than in control ovaries. Treatment with PMSG from days 7 to 9 restored the rate of oocyte nucleolar growth in nudes to control levels. PMSG also increased the number of follicles commencing growth in both nudes and controls and the differences in the numbers of primordial and trilaminar follicles were no longer detectable. The data demonstrate that abnormalities in the ovarian follicle population of the nude are detectable as early as the 10th day of life and can be reversed by treatment with exogenous gonadotrophin. These results are discussed in relation to the role of the thymus gland in ovarian development and the competence of the early juvenile ovary to respond to gonadotrophin.