Ovarian development in athymic nude mice. The size and composition of the follicle population.

Mice homozygous for the Mendelian recessive mutation nude show a reduction in the size and changes in the composition of the ovarian follicle population. Follicular loss was first evident at 2 months of age and was specifically due to a reduction in the numbers of small (primordial) follicles and medium follicles in the initial growth stages. The first ovulation was delayed until 2 1/2 months of age. By 4 months an overall reduction in all fractions of the follicle population had occurred and ovulation had ceased. These developmental changes are discussed in relation to the role of the thymus gland in sexual maturation and reproductive function in the female mouse.