Changes in hypophyseal hormones associated with accelerated aging and tumorigenesis of the ovaries in neonatally thymectomized mice.

Neonatal thymectomy at 3 days of age in mice results in ovarian dysgenesis, characterized by early follicular and oocyte loss, followed by a high incidence of ovarian tumorigenesis. Thymectomized animals with dysgenetic ovaries had extremely high levels of circulating PRL and gonadotropins before the appearance of the ovarian tumors, supporting the hypothesis that prolonged stimulation by gonadotropic hormones induces ovarian tumors. The levels of LH and FSH, however, were low by the time the tumors actually appeared, indicating a lag period between hormonal stimulation and the actual onset of the tumors. The data suggest that since thymectomized female mice exhibit a hastening of reproductive aging, these animals may be useful models for studying aging of the reproductive system, including the hormonal events which precede tumorigenesis.