Oestrogens in the plasma of the sheep foetus.

Abstract

Oestradiol-17α is the only oestrogen which has been identified in sheep foetal tissues (Velle, 1963). Oestrogens have been detected in blood (Skrzeczkowski, Dobrowolski & Domanski, 1967) and urine (Fevre & Rombauts, 1966) of the pregnant ewe. The oestrogen values reported have been very low relative to those in man. In contrast, this paper reports very considerable oestrogen concentrations in the plasma of the sheep foetus. Blood was drawn by heart puncture from foetuses within about 15 min. of slaughtering ewes at the city abbatoirs. The blood was collected into ice-cold heparinized bottles, centrifuged, and the plasma stored at −15° until analysed. Gestational ages were estimated from crown-rump lengths. To determine the oestrogen conjugates present, plasma was extracted with ether ('unconjugated fraction'), then incubated with molluscan β-glucuronidase (Koch-Light) in the presence of sodium dihydrogen phosphate to inhibit sulphatases (Dodgson & Spencer, 1953), and re-extracted with ether to give the 'glucosiduronate