FOLLICULAR DEVELOPMENT AND OOCYTE MATURATION IN HYPOGONADOTROPIC WOMEN EMPLOYING RECOMBINANT FOLLICLE-STIMULATING-HORMONE - THE ROLE OF ESTRADIOL

Both luteinizing hormone (LH) and follicle-stimulating hormone (FSH) a re required for follicle development and oestrogen production. Moreove r, under normal conditions a close association between dominant follic le size and serum and intrafollicular oestradiol levels is observed. W ith the recent availability of human recombinant FSH (recFSH), it was possible for the first time to study effects of FSH alone, in the comp lete absence of endogenous or exogenous LH, on ovarian function. Recen t studies applying recFSH in hypogonadotrophic women have shown convin cingly that normal growth of follicles up to the preovulatory stage oc curs despite extremely low oestradiol levels, in keeping with previous observations using exogenous gonadotrophins in women incapable of syn thesizing oestradiol due to steroid enzyme abnormalities. Insufficient data are presently available in humans to conclude whether or not ooc yte quality is compromised under these circumstances. It should, howev er, be realized that sufficient oestradiol levels are required for fer tilization in vivo. Therefore LH, or human chorionic gonadotrophin (HC G), should be added to stimulation protocols in hypogonadotrophic indi viduals. These observations may also be relevant for monitoring of ova rian response during recFSH therapy, especially when combined with gon adotrophin-releasing hormone agonists for ovarian hyperstimulation for in-vitro fertilization.