Isolation and characterization of a mouse embryonic stem cell line that contributes efficiently to the germ line

Embryonic stem (ES) cells have proven vital for introduction of pre-defined genetic modifications into mouse germ line. Here, we describe the isolation of a mouse ES cell line namely, R1.9 through sub-cloning and karyotyping. R1.9 ES cells have normal chromosomal complement and contribute extensively to chimaerism and germ line. We have been successfully using R1.9 ES cells in our laboratory for creation of novel strains of mouse through gene targeting.