Passive immunization with anti-oestradiol antibodies during the luteal phase of the menstrual cycle potentiates the perimenstrual rise in serum gonadotrophin concentrations and stimulates follicular growth in the cynomolgus monkey (Macaca fascicularis).

Three unilaterally ovariectomized cynomolgus monkeys, in which menstrual cycles were driven by pulsatile infusion of synthetic GnRH at a fixed frequency of 1 pulse/h, were provided with a continuous infusion of ovine anti-oestradiol gamma-globulin beginning 13 days after ovulation and continuing for 7 days thereafter. Plasma concentrations of both FSH and LH rose at the start of the antibody infusion and remained elevated throughout the 7-day treatment regimen when compared with control (non-immune gamma-globulin-treated or untreated) animals. Morphometric examination of ovaries at the end of the experimental and control infusions revealed a significant difference (P less than 0.05) in the average size of the largest non-atretic antral follicle in each of the experimental animals when compared with that of the control animals (2.45 +/- 0.23 vs 1.30 +/- 0.53 mm). Collectively, the 3 control animals possessed 9 non-atretic antral follicles greater than 1.0 mm diameter, none of which exceeded a diameter of 2.0 mm. In contrast, the experimental animals had 28 non-atretic follicles of greater than 1.0 mm diameter, 8 of which exceeded 2.0 mm. These observations are consistent with the hypothesis that oestrogen and progesterone are the primary agents responsible for the restraint of gonadotrophin secretion and preovulatory follicular growth during the luteal phase of the primate menstrual cycle.