Serum Levels of FSH and LH During the Menstrual Cycle of the Chimpanzee12

Abstract

The serum levels of FSH and LH were measured throughout the menstrual cycle of four chimpanzees by means of human gonadotropin radioimmunoassays. A midcycle LH peak was observed during each cycle. Two periods of elevated FSH levels were noted; one early in the cycle commencing near the time of onset of menstruation; the second at or near the time of the midcycle LH peak. In one animal that became pregnant, a second rise in the levels of LH, presumably due to cross reactivity in the assay by chorionic gonadotropin, occurred 10 days after the first LH peak. The data suggest that the fluctuations in FSH and LH during the menstrual cycle and early pregnancy are similar in chimpanzees and women.