Effects of gonadotrophin deficiency on follicular development in hypogonadal ( hpg ) mice

The rates of follicle growth and death in GnRH-deficient hypogonadal (hpg) mice and in normal mice were studied using the stochastic compartmental model of follicle dynamics. The rate estimates derived from this model suggest that in normal mice gonadotrophins act at several stages in the development of ovarian follicles. Gonadotrophins appear to regulate the number of follicles beginning to grow by controlling both the rate at which non-growing follicles enter the growing pool and the loss of non-growing follicles to atresia. They also appear to promote the growth of medium-sized follicles by reducing the rate of loss to atresia of these follicles rather than by stimulating growth per se. Furthermore, these data suggest that an intra-ovarian autoregulatory mechanism may exist to control the number of large follicles that are formed.