Culture of murine embryonic stem cells.

Appropriate culture of murine embryonic stem cells is critical to enabling introduced mutations to be passed through the germ line. ES cells must be carefully cultured to ensure that pluripotency is maintained. The feeder cells and foetal calf serum used to culture the cells can significantly influence germ line transmission potential. Additionally, ES cells can be karyotypically unstable, so determining the karyotype of ES cell lines will increase your confidence in the ability of the manipulated cells to contribute to the germ line in chimaeric mice.