Efficacious cryopreservation of 2 - cell stage mouse embryos via

S Introduction ince Whittingham et al. first succeeded in cryopreserving mouse embryos in 1972, there has been remarkable progress in both basic and applied research enabling us to preserve the embryos of at least 13 more mammalian species. Moreover, every process used for freezing and thawing embryos has been refined and extremely simplified. Specifically: 1) The time required for the embryo to progress from freezing to storage temperature has been significantly shortened. 2) Sucrose was added to the cryoprotectant solutions to osmotically dehydrate the embryos prior to cooling. Sucrose also reduces the osmotic swelling that occurs during the dilution of the cryoprotectants. 3) Immediately after warming and thawing, recovered embryos were transferred into either the oviducts or uteri of recipient females, and 4) Embryos were vitrified during the Original Contribution Kitasato Med J 2015; 45: 124-129