ISOFORMS OF HUMAN RECOMBINANT FOLLICLE-STIMULATING-HORMONE - COMPARISON OF EFFECTS ON MURINE FOLLICLE DEVELOPMENT IN-VITRO

The effects of three isoforms derived from recombinant human FSH on ov arian follicle development in vitro were characterized for the first t ime. The three subfractions comprised discrete pi ranges of 3.6-4.6 (a cid), 4.5-5.0 (mid), and 5.0-5.6 (least acidic). Follicular growth, es tradiol secretion, and antral formation were assessed for each fractio n of isoforms in a range of concentrations over a 5-day culture period . Least acidic FSH produced, at and above 1.5 ng/ml, a high percentage of follicles growing above the size threshold necessary for antral fo rmation, whereas mid and acid FSH induced similar growth only at highe r concentrations (7.5 ng/ml and 50 ng/ml, respectively). Least acidic FSH specifically induced the most rapid growth of follicles during pre antral development. Acid FSH at all concentrations stimulated estradio l-17 beta secretion later during culture and antral formation in a low er proportion of follicles than did least acidic and mid FSH, It can b e concluded 1) that the least acidic isoform induced fastest preantral growth, producing the largest antral follicles at the lowest dose of all three fractions and 2) that the less and mid acidic isoforms had m ore impact on stimulation of estradiol production and antral formation than the acid isoform.