SYNTHESIS OF PROLACTIN BY HUMAN DECIDUA INVITRO

To determine whether human decidua and/or chorion synthesizes and secretes prolactin [PRL], explants of decidua obtained at Caesarian section and explants of chorion from the membranes separating dizygotic twins were cultured for periods of up to 6 days. The decidual explants released 366 .+-. 37 ng PRL/100 mg tissue (mean .+-. SD) during each day in culture and incorporated 3H-labeled amino acids into immunoprecipitable prolactin. In the radioimmunoassay for PRL, serial dilutions of incubation medium displaced 125I-labeled PRL parallel to the displacement by pituitary PRL and the PRL in the medium eluted from Sephadex G-150 in a position identical to that of pituitary PRL. Chorionic explants released PRL into the incubation medium during day 1 of culture only and did not incorporate 3H-labeled amino acids into PRL. Prolactin is apparently synthesized by the decidua and not by the chorion; thus, the decidua is the source of PRL in amniotic fluid.