Interrelationship between the early embryo, embryonic stem (ES) cells, and embryonic carcinoma (EC) cells. ES can cells can be derived in vitro from the ICM(inner cell mass) of blastocysts. Like the epiblast of the egg cylinder, ES cells can form transplantable teratocarcinomas if inoculated into syngeneic adult hosts. The stem cells of these tumors (EC cells), like ES cells, can participate in normal development if introduced into a blastocyst. Both can contribute to the somatic tissues of liveborn chimeras, but, unlike EC cells, ES cells colonieze the germ line at high frequency, allowing their genotype to be transmitted to subsequent generations. EG cell lines, showing all the characteristics of ES cells, can be isolated directly in vitro from the posterior portion of 8.5-day p.c. embryos, the region that contains the primordial germ cell population.
Figure 33, page 94 from Hogan, B., R. Beddington, F. Costantini and E. Lacy 1994. Manipulating the Mouse Embryo; A Laboratory Manual. 497 pages.