Task: Named Entity Recognition
Input (English):  Villous cytotrophoblastic cells were isolated by sequential enzymatic digestion of chorionic villi from the first trimester , second trimester and term placenta and purified on a discontinuous percoll gradient , as described previously . 47 - 49 These cells were positively stained for cytokeratin 7 at 95 % , indicating the cytotrophoblastic origin of the cells .
Output (English): placenta