Changes in concentrations of serum prolactin, FSH, oestradiol and progesterone and of the sex skin during the menstrual cycle in the mangabey monkey (Cercocebus atys lunulatus).

Daily blood samples were collected from 6 regularly menstruating mangabey monkeys. Because serum LH could not be measured by a radioimmunoassay for human LH, Day 0 was taken as the day of maximum serum oestradiol concentration. The hormone patterns were very similar to those of other cercopithecids and women. However, the peak of serum progesterone was lower in mangabeys than in women. There was no distinct peak of serum oestradiol during the luteal phase of mangabeys but the average levels were higher than during the early follicular phase, a pattern more similar to that in other non-human primates than in women. Serum prolactin rose by about 50%, 48 h after the serum oestradiol peak, then declined during the mid-luteal phase before rising at the end of the cycle. Changes in the sex skin dimensions followed the same pattern as the serum oestradiol concentrations.