REGULATION OF HUMAN PLACENTAL DEVELOPMENT BY OXYGEN-TENSION

Cytotrophoblasts, specialized placental cells, proliferate early in pr egnancy and then differentiate into tumor-like cells that establish bl ood flow to the placenta by invading the uterus and its vasculature. I n this study, cytotrophoblasts cultured under hypoxic conditions (2 pe rcent oxygen), mimicking the environment near the uterine surface befo re 10 weeks of gestation, continued proliferating and differentiated p oorly. When cultured in 20 percent oxygen, mimicking the environment n ear uterine arterioles, the cells stopped proliferating and differenti ated normally. Thus, oxygen tension determines whether cytotrophoblast s proliferate or invade, thereby regulating placental growth and cellu lar architecture.