The distribution of two cell surface determinants of mouse embryonal carcinoma and early embryonic cells.

This study examines the distribution of two carbohydrate determinants recognized by monoclonal antibodies EMA-1 and EMA-6 on cells in culture, adult mouse tissues and day 0-7 embryos, and provides partial biochemical characterization of the molecules carrying the determinants for EMA-1 on embryonal carcinoma cells. Both antigens are present on primordial germ cells of day 8-day 10 mouse embryos (Hahnel and Eddy, 1986), and are expressed recurrently on pluripotent cells during earlier embryogenesis. Both antigens are also present on mouse embryonal carcinoma cells and the same set of adult tissue types. However, the distribution of the EMA-6 determinant on adult urogenital epithelia and during embryogenesis is more restricted than that of EMA-1. The determinants are detected only on lumenal surfaces of epithelial cells, suggesting that they are either not involved in processes of cell-cell or cell-substrate interaction, or are masked or altered during such interactions. Present biochemical evidence suggests that EMA-1 determinant on Nulli SCC1 cells may be on a large glycoprotein or a glycoprotein complex that is firmly attached to the cell membrane.