Chorionic gonadotropin secretion during pregnancy in the chimpanzee (Pan troglodyte).

Abstract

SummaryQuantitative alterations in urinary gonadotropin excretion were studied throughout pregnancy in two chimpanzees (Pan troglodyte). Weekly urine samples were collected following mating and gonadotropic activity determined by the increase in ovarian weights of immature female rats. Gonadotropic activity was first detected during weeks 1 and 2 postmating, and had reached peak titers by days 30 to 40. These levels persisted for 2 to 3 weeks and declined rapidly, thereafter, to low, but detectable, levels which were maintained until 1 to 3 weeks prepartum. Reproductive cyclicity as determined by periodic swelling and detumescence of the genital and anal region disappeared during lactation. Biological and immunological tests of extracts from pregnant chimpanzee urine indicate a close relationship to human chorionic gonadotropin and the temporal changes in gonadotropic titers occurring throughout gestation are comparable to those reported for the human.The authors thank Drs. Y. T. and S. C. Li for their he...