Sexual Maturation in the Female Rhesus Monkey and the Development of Estrogen-Induced Gonadotropic Hormone Release12

Abstract

The subcutaneous administration of estradiol benzoate (EB) consistently induces acute discharges of LH and FSH in adult female rhesus monkeys but not in sexually immature animals. To determine when, during the course of sexual maturation, the hypothalamo-hypophysial unit becomes competent to respond to estrogen, single injections of EB were administered to females at various times before and after the first spontaneous vaginal bleeding. Estrogen induced gonadotropin surges were not demonstrable until 4-8 months after menarche. The pituitaries of 6 premenarchial monkeys responded to the administration of synthetic LRF by a release of gonadotropin and their content of FSH was in the adult range. Spontaneous cyclic gonadotropin discharges, which eventuated in ovulation, first occurred approximately a year after menarche. The functioning of the control system that responds to the positive feedback action of estrogen could not be advanced by chronic treatment with estradiol or progesterone. (Endocrinology94: 198, 1974)