In order to explore the possibility that human chorionic FSH (hCFSH) may be synthesized in vitro by the placenta and secreted into the culture media, chorionic tissue of the first trimester was cultivated in the radioactive medium prepared byadding 3H-proline and/or 14C-glutamic acid. Purification of biosynthesized hCFSH from the media was carried out by a combination of Sephadex G-100 gel filtration, DEAE-cellulose chromatography and polyacrylamide disc-gel electrophoresis...