Patent ID: 7294754

Claim:
A method for generating a mouse homozygous for a genetic modification, comprising: (a) introducing a female mouse embryonic stem (ES) donor cell into a pre-morula diploid mouse host embryo, wherein the ES donor cell is heterozygous for the genetic modification and is obtained from an inbred strain; (b) culturing the embryo of (a) to the blastocyst stage; (c) introducing the embryo of (b) into a surrogate mother for gestation, wherein a modified female mouse is generated having at least 90% cellular contribution from the female donor cell; (a′) introducing a male mouse ES donor cell into a pre-morula diploid mouse host embryo, wherein the ES donor cell is heterozygous for the genetic modification and is obtained from an inbred strain; (b′) culturing the embryo of (a′) to the blastocyst stage; (c′) introducing the embryo of (b′) into a surrogate mother for gestation, wherein a modified male mouse is generated; and (d) breeding a sexually mature modified male mouse and a sexually mature modified female mouse of (c and c′), wherein a mouse homozygous for the genetic modification is generated.