Oestrogen production by blastocyst and early embryonic tissue of various species

Abstract

Estrogen synthesis by the early embryo in vitro was studied with tissue from pigs, sheep, cows, roe deer [Capreolus capreolus], ferrets [Mustela putorius], cats, rabbits and a plains viscacha [Lagostomus maximus]. Definitive evidence for aromatase activity and estrogen synthesis in preimplantation trophoblast was obtained for the pig with the formation of estrone, estradiol-17.beta. and estradiol-17.alpha. from 3H-labeled androstenedione and dehydroepiandrosterone. Aromatase activity was appreciably lower in all other species studied, and labeled estrogens were recovered only from incubations of allantochorionic roe deer tissue, recovered shortly after implantation, and from pooled samples of early embryonic cow tissue. High aromatase activity in preimplantation pig trophoblast was associated with the maternal pregnancy recognition and the occurrence of superficial implantation in this species.