Sex hormones correlated with sex skin swelling and rectal temperature during the menstrual cycle of the pigtail macaque (Macaca nemestrina).

Daily measurement of serum luteinizing hormone, estradiol-17beta, and progesterone were made during the menstrual cycle in nine pigtail macaques (Macaca nemestrina). All data were normalized to the day of the luteinizing hormone peak. Serum estradiol-17beta increased from approximately 100 pg/ml during the early follicular phase to 442 +/- 156 pg/ml during the maximum midcycle concomitant with the luteinizing hormone peak, and a small increase in serum estradiol-17beta was observed during the luteal phase coincident with the progesterone peak. Serum progesterone values increased slightly at the time of the luteinizing hormone peak and increased from 0.2-0.3 ng/ml during the midfollicular phase to peak levels of 8.3 +/- 1.75 ng/ml 9 days after the luteinizing hormone surge. Serum luteinizing hormone remained low and relatively constant throughout the early and midcycle, then sharply increased approximately four-fold to peak values of 6.25 +/- 0.9 ng/ml. Sex skin swelling increased slowly during the follicular phase and declined slowly throughout the early luteal phase. Rectal temperature did not change significantly throughout the menstrual cycle. The similarity of plasma sex hormone changes during the menstrual cycle between women and the pigtail macaque suggested that this nonhuman primate should be a useful animal model for studying human reproduction.