Abstract
The removal of the thymus gland at birth from the female Wistar rat disrupts the size distribution and number of ovarian follicles by the 10th day of life and culminates in ovarian dysgenesis at 130 days of age. From birth until 50 days of age the effects of athymia are specifically reflected in the number of primordial follicles and follicles in the initial, preantral, growth stages. Ovarian failure in the neonatally thymectomized rat is initiated during the first 2 wk of life.