Alteration in circulating LH level and in cervical mucus induced by mid-cycle progesterone in chimpanzees.

Administration of 200 micrograms mestranol/day (oestrogen) to ovariectomized chimpanzees caused a rapid decrease of circulating gonadotrophin concentrations to values similar to those in intact females. Administration of 2 mg chlormadinone acetate (progestagen) resulted in a prompt and significant rise in LH and FSH. This rise was accompanied by alteration in the physical characteristics and electrolyte composition of the cervical mucus which were the same as those observed around the time of ovulation. These results suggest a role of preovulatory progesterone secretion in relation to changes associated with ovulation in the chimpanzee.