Mouse Embryo Cryopreservation by Slow Freezing

This embryo cryopreservation protocol is used by The Jackson Laboratory and several other repositories around the world. This protocol has clearly withstood the test of time; >2 million embryos from thousands of strains have been cryopreserved using this method. It requires a controlled-rate freezer, but is simple, effective, and can be applied to cryopreserve embryos from the two-cell to the blastocyst stage. Thawing requires neither special media nor equipment because the insemination straw contains all of the needed elements, making this very useful for distributing cryopreserved embryos. Embryo survival rates of greater than 90% can be expected when this method is used, making it reliable and enabling staff with prior embryo-handling experience to become proficient quickly.