OESTRIOL METABOLISM IN THE HUMAN FOETO-PLACENTAL UNIT

Abstract

At laparotomy 1 to 2 [mu]c amounts of estriol-16-14C were injected into the umbilical vein of 3 fetuses and the feto-placental unit was left in situ with an intact circulation for a few minutes prior to the removal of the products of conception. More than 90% of the radioactivity present in the various fetal tissues consisted of estriol-3-sulphate. In addition, a small amount of estriol-16(17?)-glucosiduronate was identified in extracts of fetal liver. In contrast to the pattern found in fetal tissues, the bulk of radioactivity in the placenta and membranes was present as unconjugated estriol. In two cases at laparotomy the placenta was disconnected from the fetus and was perfused in situ with 0.4 [mu]c of estriol-16-14c-3-sulphate. More than 80% of the radioactivity present in the placenta was identified as unconjugated estriol. The results indicate that estriol-3-sulphate formed by the fetus becomes nydrolyzed to a significant extent by the placenta.