OVARIAN INFLUENCE ON THE RESPONSE OF THE ANTERIOR PITUITARY TO ESTROGENS

Abstract

There are two theories of the action of sex hormones on the gonadotrophic functionof the hypophysis. One theory is that sex hormones (estrogens or androgens) inhibit or suppress the gonadotrophic function of the hypophysis; the other is that the sex hormones stimulate the hypophysis to elaborate and release increased quantities of gonadotrophic hormone. Review of the evidence supporting these concepts indicates that one is based on the resultsof long-term experiments and the other on interpretation of short-term experiments. Long-term experiments are those in which the rats, although immature initially, reached the normal age of maturity during the course of treatment. Furthermore, since the estrous cycle of the rat is 4 or 5 days in length and the gestation period is 22 days, many of the long-term experiments exceeded these normal reproductive processes in duration. The duration of short-term experiments more closely approximates the length of the sexual cycle.