Ovarian development in athymic nude mice. II. The growth of the oocyte and follicle.

Congenitally athymic mice homozygous for the Mendelian recessive mutation "nude" develop well defined morphological and quantitative changes in the ovarian follicle population. A decline in follicle numbers at 2 months of age is preceded by a retardation in follicle growth at 1 month of age. The growth of the oocyte and its nucleus are not affected by the nude mutation. However, the rate of growth and maximum size of the oocyte nucleolus are reduced in nudes. These developmental events are discussed in relation to the genetic activity of the oocyte, the role of pituitary gonadotrophins in follicular and oocyte growth and the possible role of the thymus gland in these processes.