In vitro biosynthesis of TSH- and LH-releasing factors by the human placenta.

Human chorionic membrane and human placental tissue contain substances with the same elution volume as hypothalamic TRF and LRF standards during separation by carboxyl-methyl-cellulose ion-exchange chromatography. Homogenates prepared from fresh human placentas delivered at term caused release of TSH (thyroid-stimulating hormone) and LH (luteinizing hormone) when bioassayed in rats. After dialysis of placental homogentes, synthesis of biologically active TSH-and LH-releasing factors can be shown to occur in vitro following the addition of appropriate precursor amino acids and cofactors.