ABSTRACT
Chapters 2 and 3 describe the use of murine ES cells in gene targeting and nuclear transfer respectively. ES cell lines were first isolated by Evans and Kaufman (4), and independently, by Gail Martin (5) in 1981. Their experiments were inspired by the properties of the stem cells of germ cell tumors known as embryonal carcinoma or EC cells (see Chapter 6). EC cells had been shown to contribute to somatic tissues when injected into the blastocoel cavity of murine preimplantation embryos, but rarely if ever, contributed to the germ line. It was evident that if that deficiency could be overcome by deriving similar cells directly from the embryo, it might provide a route to germ line modification.
