Temporal relationships of estrogen, progesterone, and luteinizing hormone levels to ovulation in women and infrahuman primates

These studies were undertaken to ascertain the interval between the estrogen and LH peaks and ovulation in women, rhesus monkeys, and baboons. Estrogen, progesterone, and LH were measured by RIA. Ovulation was documented by visual examination of the ovaries, histology of the corpora lutea, and recovery of ova. The data for human subjects was based on a group of 23 normal women scheduled for surgical sterilization. Blood was drawn daily between 8:30 and 10:30 p.m. beginning on day 10 of the cycle. Surgery was performed 1 to 5 days after the LH peak. The hormonal findings were correlated with the histology of the corpus luteum. The mean interval from the estrogen peak to ovulation was 34 hours, the interval from the estrogen peak to the LH peak was 24 hours, and that from the LH peak to ovulation was 9 hours. In 46 rhesus monkey cycles and in 53 baboon cycles diagnostic serial laparoscopic examinations were initiated following the estrogen peak and repeated every 24 hours until ovulation was confirmed. The mean interval between the estrogen peak and ovulation was 34 hours in the monkey and 41 hours in the baboon. The intervals from the estrogen peaks to the LH peaks were 12 hours in the monkey and 23 hours in the baboon. The intervals from LH peak to ovulation were 22 hours in the monkey and 18 hours in the baboon. Plasma progesterone levels were significantly increased prior to the LH peak in all three species.