A comparative study of progesterone synthesis by term human fetal amnion and chorion

Abstract

Activity of 3 beta-hydroxysteroid dehydrogenase-5, 4-en isomerase was investigated with [7n-3H] pregnenolone as substrate in the homogenates of amnion and chorion collected from women (n = 6, age 20-34 years) after spontaneous labour at term (37-40 weeks gestation) from uncomplicated pregnancies. Controls were heat-denatured homogenates instead of fresh homogenates. Reverse-isotope dilution analysis gave positive identification of [3H] progesterone in all incubations of viable tissues. This metabolite was not evident in the controls. The extent of enzymic conversion of chorion, 1.4-31.1% was consistently higher than that of the amnion, 0.66-1.7%. The results show that the human fetal membranes can be a source of progesterone during pregnancy. The metabolic capability may have physiological significance in the induction and progression of labour to parturition.

Evidence for Progesterone Synthesis by Human Umbilical Cord Blood Erythrocytes

“…It is now clear from our previous studies that steroidogenesis occurs at other tissues such as the fetal membranes [6] and umbilical cord [7]. Considering the important role of progesterone in the endocrinology of human pregnancy, these findings emphasize the need for more information concerning the steroidogenic capability of umbilical cord blood erythrocytes and raise the question whether these blood cells possess 3ß-hydroxysteroid dehydrogenase ability to convert pregnenolone to progesterone.…”