To utilize fluorescein-labeled antisera against B17-estradiol-BSA conjugates and to determine by means of the immunofluorescent histochemical method for steroid hormones the initial time of estrogen production by the gonads of the chick embryo. To determine the initial time of secretion of testosterone and B17-estradiol by the gonads of the chick embryo by assaying for these steroid hormones in the blood using the technique of radioimmunoassay. In both instances (1 and 2) the effect of hypophysectomy on the times of initial synthesis, as well as sustained production and secretion of these steroid hormones will be evaluated. The effects of pituitary deprivation will be ascertained by histochemical (immunofluorescent) examination of the gonads and determination of blood steroid hormone levels of intact embryos, hypophysectomized embryos, and hypophysectomized embryos with pituitary transplants to the chorioallantoic membrane.