Pregnant rhesus monkeys (Macaca mulatta) were hypophysectomized at 8-10 weeks gestation to determine effects on plasma levels of estrone (E1), estradiol-17beta (E2), and progesterone (p). The first group of monkeys was subsequently fetectomized at 107-114 days. After hypophysectomy there was an initial decrease in maternal peripheral plasma E2 followed by a rise to preoperative levels within 4-5 weeks. Plasma levels of E1 and P were not markedly altered. After fetectomy, peripheral estrogen concentrations, especially E2, declined markedly. In the second experimental series, we have examined the effects of maternal hypophysectomy on levels of E1, E2 and P either (1) in both mother and newborn baby or (2) in mother, term fetus and umbilical vein. Groups of hypophysectomized and intact pregnant monkeys (3 each) were delivered by cesarean section at the expected time of parturition. Other hypophysectomized and intact monkeys (2 each) delivered normally. E2 levels were elevated significantly in plasma of hypophysectomized monkeys at the time of cesarean delivery and in newborn babies of hypophysectomized mothers shortly after parturition. Escept for these differences, the maternal hypophysis apparently is not a major factor in the control of E1, E2 and P concentrations in pregnant rhesus monkeys.

Animals↗

PubMed1975

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

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.

Animals↗

PubMed1975

Duration of chorionic gonadotropin production by the placenta of the rhesus monkey.

Concentrations of macaque chorionic gonadotropin (mCG) in placenta, blood and urine of rhesus monkeys have been measured by both radioimmunoassay and bioassay throughout gestation. mCG was easily detected and quantified in these specimens for a brief period in early pregnancy, but was not detectable between the 40th day of pregnancy and term in placental extracts, serum, or 40-fold urine concentrates. The apparent absence of mCG after the 40th day of pregnancy makes these macaques a valuable model for pregnancy research, where the absence of chorionic gonadotropin is experimentally desirable. Unlike women and some higher primates, the functional status of the fetal, placental and maternal endocrine compartments of macaques can be studied in the absence of circulating chorionic gonadotropin during mid and late gestation.

Animals↗

PubMed1974