Abstract: Novel cultured inner cell mass (CICM) cells, and cell lines, derived from ungulates, in particular, pigs and cows, and methods for their preparation are provided. The subject CICMs possess similar morphology and express cell markers identically or substantially similarly to ICMs of undifferentiated developing embryos for prolonged culturing periods. Heterologous DNA is inserted into the subject CICM cells and cell lines so as produce transgenic CICM cell which are introduced into non-human fertilized embryos to produce transgenic chimeric embryos. The transgenic chimeric embryos are transferred into recipient females where they are permitted to develop into transgenic chimeric fetuses. Recipient females give birth to transgenic chimeric animals which are capable of transmitting the heterologous DNA to their progeny. Transgenic CICM cells are also used to produce cloned transgenic embryos, fetuses and offspring.

Abstract: A culture system for producing PGCs or EG cells by culturing PGCs for long periods in tissue culture is provided. This culture system uses LIF, bFGF, IGF and SCF. The resultant EG cells are useful for the production of transgenic and chimeric avians, in particular, chickens and turkeys, and also for cloning purposes.

Abstract: A culture system for maintaining avian PGCs for long periods in tissue culture is provided. This culture system uses LIF, bFGF, IGF and SCF. The resultant PGCs are useful for the production of transgenic and chimeric avians, in particular, chickens or turkeys.

Abstract: An improved method of nuclear transfer involving the transplantation of donor differentiated cell nuclei into enucleated oocytes of the same species as the donor cell is provided. The resultant nuclear transfer units are useful for multiplication of genotypes and transgenic genotypes by the production of fetuses and offspring, and for production of isogenic CICM cells, including human isogenic embryonic or stem cells. Production of genetically engineered or transgenic mammalian embryos, fetuses and offspring is facilitated by the present method since the differentiated cell source of the donor nuclei can be genetically modified and clonally propagated.