title: Gene targeting in C57BL/6 ES cells. Successful germ line transmission using recipient BALB/c blastocysts developmentally matured in vitro.
abstract: There are significant advantages to the production of gene-knockout mice directly in mouse strains other than 129. The availability now of ES cells derived from the C57BL/6 mouse strain presents workers with a valuable alternative. A major difficulty, however, is the requirement for BALB/c blastocysts as recipients for ES cell injection. Using standard procedures, few BALB/c blastocysts can be obtained. This limitation has now been resolved by harvesting BALB/c embryos at the early morula stage and maturing these to blastocysts by in vitro culture. Of early morulae harvested and cultured, over 70% were recovered as fully expanded and injectable blastocysts. C57BL/6 ES cell injection of these blastocysts has enabled the production of a number of gene-knockout mice with a success rate similar to that reported for ES cells derived from the 129 mouse strains.
authors.affiliation: Centenary Institute of Cancer Medicine and Cell Biology, Royal Prince Alfred Hospital, Sydney, NSW, Australia.
authors.forename: F A
authors.initials: FA
authors.lastname: Lemckert
authors.forename: J D
authors.initials: JD
authors.lastname: Sedgwick
authors.forename: H
authors.initials: H
authors.lastname: Körner
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000166:cytology / Q000378:metabolism*; D002454:Cell Differentiation / Q000235:genetics; D002478:Cells, Cultured; D018014:Gene Transfer Techniques; D005854:Germ Cells / Q000166:cytology / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008845:Microinjections; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism*