Tetraploid Complementation Assay

The generation of mouse chimeras by combining host embryos with genetically modified embryonic stem (ES) cells is a necessary step towards establishment of genetically modified mouse strains. This protocol describes the procedures necessary for the production of mouse chimeras by tetraploid complementation assay. This technique can be used to generate ES cell-derived embryos or animals, and to rescue extraembryonic defects. It provides a powerful tool for direct analysis of phenotype and for studies of cell fate during mouse development. This method can speed up the production of genetically modified strains directly from hybrid ES cells. The Transgenic facility at the Samuel Lunenfeld Research Institute of Mount Sinai Hospital and more recently at the Toronto Centre for Phenogenomics has been successfully using this protocol since early 1990s.