Histologic characteristics of cells cultured from rat placental tissue

Laboratory animals, especially rats, have provided a comparative model for extensive research on maternal-fetal relationships. To identify individual placental cells for subsequent immunologic analysis, cultures of rat placentas were studied. Five cell types were observed, including: two histologically distinct giant cells, mononucleate and multinucleate, apparently formed by amitosis and fusion, respectively; small round cells; polygonal cells, probably cytotrophoblasts. Of particular interest are the small round cells which are phagocytic and morphologically similar to macrophages, cells known to be important in the immune response.