Patent ID: 7071373

Claim:
A method for making a chimeric ungulate comprising: (a) introducing at least one a cultured ungulate embryonic stem cell from a cultured ungulate embryonic stem cell line, wherein said cells grow in multilayers and wherein said embryonic stem cells have a rounded shape as observed with the light microscope, a diameter of approximately 8–15 microns, and a cytoplasmic to nuclear diameter ratio of approximately 10–25; 75–90 as show in FIG. 2 , wherein the ratio is approximated by the cytoplasmic diameter from the periphery of the nucleus to the end of the cell, to the diameter of the nucleus, and said cell has a first genetic complement, into a recipient embryo of the same species as the embryonic stem cell, said recipient embryo having a second genetic complement which differs from the first genetic complement, in at least one gene, to form a chimeric ungulate embryo; and (b) placing the chimeric ungulate embryo in an environment suitable for the completion of development to form a chimeric ungulate.