term placental trophoblast cells , released by trypsin digestion of placental villi , purified on a percoll gradient and grown in serum-containing medium , differentiate within 24 to 48 h in culture from mononucleated cytotrophoblast-like cells at the start of culture to highly multinucleated giant ( syncytiotrophoblast-like ) cells that are more active in hormonogenesis .
C0032043
placental
C0008508
placental