Responsiveness of the Monkey Corpus Luteum to Exogenous Chorionic Gonadotropin
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Twelve rhesus monkeys (Macaca mulatta) were divided evenly among four experimental groups. Each group was determined by the day of initiation of human chorionic gonadotropin (hCG) treatment. They were. day of ovulation plus two days, Day +2; day of Ovulation plus six days, Day +6; plus ten days, Day +10, and plus fourteen days, Day +14. Ovulation was determined by the peak of luteinizing hormone (LH) and a laproscopic examination was performed, after the determination of the LH peak, to visually. determine if a corpus luteum was present on the ovary. Exogenous heG was administered to each group of monkeys, beginning on their respective days, in the following manner. first day, 30 I.U. heG in 0.5 ml saline; second day 60 I.U. hCG in 0.5 ml saline; third day, 90 l.U. heG in 0.5 ml saline. fourth day, 180 I.U. heG, and fifth day, 360 I.U. heG. Serum concentrations of progesterone and estradiol were measured by use of radioimmunoassays. These values were then compared to mean serum concentrations of normal menstrual cycles of rhesus monkeys '(Hodgen, et ale 1976). In the Day +2 group, both the progesterone and estradiol concentrations increased and were maintained as long as the heG was present in the systems. Much the same thing happened in the Day +6 study group, but to a much greater degree. Both concentrations rose the day after the initial injection of heG, but the estradiol peaked two days after the progesterone peaked. The Day +10 reaction 2 simulates the reaction of the hormone concentrations if the monkey was pregnant. Chorionic gonadotropin would show up in a pregnant monkey's system, usually on the tenth day to "rescue" .tl1e corpus luteum (Knobil' 1973. Surve et al. 1973, Bosu and Johansson 1975). Therefore, the functional life of the corpus luteum was lengthened about four days. The only real effect which occured in the nay+14 group was the greater functional life span of the corpus luteum. There was some rise in the serum concentration of the hormones, enough to maintain pregnancy, but not as much as in the other groups. For all except one monkey, the corpora lutea's life spans" were increased by five days. In the other monkey, menses began the day after the first injection of hCG.