Molecular and Cellular Aspects of Embryonal Carcinoma Cell Differentiation

Embryonal carcinoma cells represent a subpopulation of undifferentiated stem cells contained within a mixture of differentiated cell phenotypes of teratocarcinoma tumors (1). Such tumors can develop spontaneously in gonadal tissue of certain mouse strains (2,3) and can be induced experimentally (4,5). The undifferentiated EC cells are the primary malignant cells of the tumor and are similar to early embryonic ectoderm morphologically (6), biochemically (7) and antigenically (8). Like early ectoderm cells, EC cells are pluripotent since injection of EC cells into host blastocysts leads to formation of chimeric mice (9–11).