Pituitary control of estrogen secretion in the chick embryo: true or spurious?

The aim of the present study was to examine whether the hypophysis played a role in ovarian 17 beta-estradiol secretion in the chick embryo. Hypophysectomy was fulfilled by partial decapitation, which has long been codified as a practical method of hypophysectomy in the chick embryo. Ovaries from decapitated, sham-operated, and intact embryos 9-19 days old were cultured in vitro during a 4-hr period, and 17 beta-estradiol released was determined by radioimmunoassay. A difference in estradiol secretion rate between decapitated and control embryos was noticed at 10-13 days, on both a per ovary and a per gram basis. At 15-19 days, there was no difference. These results suggest that the hypophysis influences the estrogen secretion of the chick embryo ovary during a limited space of time.