Recruitment of an ovulatory follicle in the human following follicle-ectomy and luteectomy.

The study was undertaken to explore the time required for the selection and ovulation of a dominant follicle after interference with the normal menstrual cycle of fertile women. At routine laparotomy (sterilization) a leading follicle or a fresh corpus luteum was excised, and the day of the next ovulation was estimated by monitoring of serum levels of luteinizing hormone (LH), follicle-stimulating hormone (FSH), progesterone, and 17 beta-estradiol and by registration of the growth of the follicles through ultrasonic scanning. The results are in accordance with earlier observations in the rhesus monkey demonstrating that the recruitment and selection of an ovulation-competent follicle takes 12 to 14 days in the primate. Since this time is close to the length of the normal follicular phase and approximately the same after follicle-ectomy and luteectomy, the results suggest an importance of local factors in regulating follicle recruitment.