[Cryopreservation of embryos and gametes in mice]

Embryos, oocytes and spermatozoa of mice could be successfully preserved at -196 degrees C by simple freezing methods. The survival rate of frozen embryos was very high at thawing and they developed into normal young after embryo transfer. In gametes, the cryopreserved oocytes could be fertilized in vitro by fresh spermatozoa and the cryopreserved spermatozoa could fertilize fresh oocytes. Moreover, the cryopreserved oocytes could be fertilized by the cryopreserved spermatozoa and the embryos obtained by in vitro fertilization between cryopreserved gametes could develop into normal, live young after embryo transfer. In the future, if not only the embryos but also the oocytes and spermatozoa of many mouse strains are frozen, normal young can be produced from cryopreserved embryos and gametes.