Effect of partial decapitation (hypophysectomy) on 17β-estradioI secretion by the chick embryo ovary

Ovaries of equally matched partially decapitated (hypophysectomized) and sham-operated (at 42 h of incubation) 11 1/2-day-old chick embryos, i.e. embryos as identical as possible as regards body size and other morphological features, were compared with respect to the amounts of 17 beta-estradiol secreted during a 4 h-culture period. The 17 beta-estradiol secretion rate was very significantly lower in the decapitated than in the control embryos. This result suggests that the hypophysis controls 17 beta-estradiol secretion of the ovary in the 11 1/2-day old chick embryo.