The persistence of "steroid-synthesizing cell" antigen and 3beta-hydroxysteroid dehydrogenase in organ cultures of normal human placentas.

The syncytiotrophoblast of chorionic villi of normal human mid-pregnancy placenta maintained in organ culture in a chemically-defined medium loses its various differentiated characters at different rates. Although certain oxidative and hydrolytic enzymes are retained for periods of 1-6 weeks and human placental lactogen persists in the cytoplasm for about 2 weeks, the enzyme 3β-hydroxysteroid dehydrogenase and the “steroid-synthesizing cell” antigen are lost after culture for 1 and 2 days respectively. These two characters reappear in cytotrophoblast that is newly differentiated during culture. It is concluded that organ cultures of this type will not be suitable for metabolic studies on the biosynthesis of steroid hormones by the placenta.