Patterns of Circulating Luteinizing Hormone and Their Relation to Plasma Progesterone Levels During the Menstrual Cycle of the Rhesus Monkey

Using a specific radioimmunoassay for rhesus monkey luteinizing hormone (LH) the concentration of this hormone in peripheral plasma and its temporal relationship to that of progesterone, as measured by a competitive protein binding assay, are described throughout the menstrual cycle. The preovulatory LH surge, lasting 1–3 days, occurred most frequently on days 10–12 of the cycle with a range of 9–21 days. This variability was limited to the portion of the cycle preceding the LH peak, the remainder being remarkably constant (14–16 days). The increase in plasma progesterone levels did not precede, but followed the LH surge. It is concluded that ovulation in this species occurs within 24 hr after the LH peak and that the patterns of circulating LH and progesterone during the menstrual cycle of the rhesus monkey closely resemble those in the human female. (Endocrinology87: 453,1970)