As a woman nears perimenopause, the number of small antral follicles recruited in each cycle diminishes and consequently insufficient Inhibin B is produced to fully lower follicle stimulating hormone (FSH) and the serum level of FSH begins to rise. Eventually the FSH level becomes so high that down regulation of FSH receptors occurs and by menopause any remaining small secondary follicles no longer have FSH receptors. Continue reading →