Chemical and biological characterization of an active substance of the human placenta

Acetic acid extracts of human term placenta have been fractionated by pH and salt precipitations and by exclusion chromatography on a Sephadex G-75 column. A partially purified fraction (F-II) possessing uterotropic activity in immature and young mice was obtained. This active fraction was submitted to the action of protein denaturating agents (heat, 8 M urea) and of specific proteolytic enzymes (trypsin, alpha-chymotrypsin and pronase). These treatments completely destroy the uterotropic activity showing that the active substance is of protein nature. The administration of F-II to spayed mice did not produce any increase in their uterine weight suggesting that the uterotropic activity would be due to stimulation of the female gonad.