Follicular development in the neonatal mouse ovary; effect of epidermal growth factor

The growth of the ovary has been studied in the mouse after administration of epidermal growth factor (EGF). Newborn females injected daily with EGF for the first 5 days of life showed a retardation of ovarian development. The number of follicles in the resting pool (small follicles) was significantly greater than in control animals and there were fewer growing follicles at more advanced stages of development (types 3b and 4). The percentage of mitotic figures in the follicular and surface epithelia of the ovary and the epithelium of the extra-ovarian rete was also significantly reduced after EGF. The results indicate that EGF may inhibit rather than promote the growth of follicles in the neonatal mouse ovary in vivo.