maturation control groups received either the combined exogeneous gonadotropins or fsh only 15 monkeys each group all of the groups received a fixed regimen of gonadotropin therapy for seven consecutive days 25 iu day im cycle days 3 9 followed by hcg 1 000 iu im on cycle day 10 it was observed that the variability in response to gonadotropin treatment was less in the group treated with the gnrh antagonist the patterns of estradiol rise in serum and the appearance of the ovaries at laparotomy were more uniform when the endogeneous gonadotropin secretion was suppressed fig2 and 3 show assay results while both treatments suppressed the estrogen variability only the regimen employing the gnrh antagonist and fsh in the absence of lh promoted maturation of multiple ovarian follicles and these follicles were ovulated by hcg with subsequent recovery of two cell embryos this is the first time that ovarian follicular maturation has been demonstrated to be promoted by fsh in the absence of detectable levels of lh in serum ovulation was also achieved in 9 of the 15 control monkeys treated with only fsh the same quantities of fsh can be employed as is employed in the conventional exogeneous fsh lh combinations generally the amount of fsh administered daily to a woman being treated will be in the range of about 75 225 iu and preferably in the range of about 1 5 4 0 iu kg day intramuscular injection can be employed the gnrh antagonist is administered in an amount which is.