GENERATION OF COMPLETELY EMBRYONIC STEM CELL-DERIVED MUTANT MICE USING TETRAPLOID BLASTOCYST INJECTION

Embryonic stem (ES) cells provide a unique tool for producing specific ally designed mutations in mice. Here, we describe an alternative appr oach toward the generation of mice which are derived completely from E S cells (ES mice), as judged by glucose phosphate isomerase (GPI) anal ysis, without prior passage through the germline. By injecting wild-ty pe and mutant ES cells into tetraploid blastocysts, viable and fertile ES mice were generated, suggesting that totipotency of ES cells was n ot affected by long-term culture and experimental manipulation in vitr o, When ES cell clones harboring a lacZ reporter gene introduced by ei ther targeted insertion or a gene-trap approach were used, the express ion pattern of the lacZ gene in ES fetuses was identical to that of fe tuses that were derived from breeding of chimeric mice. Thus, this tec hnique can be considered as a useful and rapid approach to produce fet uses and mice directly from ES cells carrying predetermined genetic ch anges and offers many applications for studies in molecular genetics a nd developmental biology. (C) 1997 Elsevier Science Ireland Ltd.