Effect of enucleation of the corpus luteum at different stages of the luteal phase of the human menstrual cycle on subsequent follicular development

Abstract

To investigate the mechanism of suppression of follicular development during the luteal phase of the human menstrual cycle, the corpus luteum [CL] was enucleated surgically from 10 women at various times after ovulation. In the 24 h after CL enucleation there was an immediate and rapid fall in the concentration of estradiol and progesterone and a temporary decline in the concentration of FSH and LH [luteinizing hormone]. Within 3 days, however, all 10 women showed evidence of renewed follicular activity as indicated by a progressive rise in the concentration of estradiol. This rise was preceded by a rise in the concentration of FSH and LH, and ovulation, as indicated by a mid-cycle surge in LH and rise in the concentration of plasma progesterone, occurred 16-19 days after enucleation. There was no significant difference in the time to ovulation following enucleation at different times of the luteal phase. The postoperative follicular phase, measured from the time of enucleation, was 3 days longer than that observed preoperatively from the 1st day of menstrual bleeding. In the follicular phase of postoperative cycles the concentration of FSH was higher and that of estradiol lower than the corresponding values before surgery. The absence of healthy antral follicles in the luteal phase of the cycle is due to the inhibitory effects of the corpus luteum. The fact that, after CL enucleation, emergence of the dominant follicle was always preceded by a rise in the concentration of FSH and LH suggests that suppression of gonadotropins by ovarian steroids secreted by the corpus luteum is responsible for the inhibition of follicular development during the luteal phase of the cycle.