Plasma estrogens, progesterone and chorionic gonadotropin in pregnant rhesus monkeys (Macaca mulatta) after...

Maternal peripheral plasma concentrations of estrone (E1), estradiol-17beta (E2), and progesterone (P) were determined in 4 rhesus monkeys ovariectomized in early pregnancy (22-24 days). After ovariectomy, plasma concentrations of E1 and E2 were basal for 1 to 2 weeks. In contrast, slightly higher estrogen levels, which may be attributed to the ovaries, were found in intact pregnant monkeys. E2 levels increased rapidly after this and exceeded those of E1 until the 5th month of gestation. From that time until parturition, E1 levels equaled or exceeded those of E2 in most instances. The pattern of P concentrations was similar to that observed in intact monkeys. Urinary chorionic gonadotropin (MCG) levels in ovariectomized monkeys were not significantly different from those found in normal pregnancies. Thus, the pattern for circulating E1, E2 and P, as well as for the excretion of MCG, after ovariectomy were remarkably similar to those found in intact, pregnant rhesus monkeys, indicating minimal ovarian influence.