Forty-five years ago today, on May 2, 1980 (March 18, 1980 in the lunar calendar), the frozen embryo transfer of sheep in China was successful. On May 2, 1980, the sheep frozen embryo transfer experiment conducted by the Institute of Animal Husbandry, Chinese Academy of Agricultural Sciences obtained the first lambs "conceived by the belly", and three lambs were born in one viviparum. All of them developed normally, and the mother and child sheep were safe and strong. In 1979, the Institute of Animal Husbandry of Chinese Academy of Agricultural Sciences used Han sheep as experimental animals to study the ultra-low temperature cryopreservation of livestock ewe embryos. The donor ewe (embryo supplier) is first treated with pituitary hormone to make the ewe superovulate to obtain more embryos. Embryos were surgically removed on the sixth to eighth day after estrus mating and pre-freezing treated with a culture medium containing antifreeze. According to a certain cooling procedure, the embryos are slowly frozen until minus 60 ¡æ, and then stored in liquid nitrogen at minus 196 ¡æ. Before frozen embryos are transferred, they are thawed according to a certain temperature increase program. In this experiment, three embryos stored at ultra-low temperature for 14 days were thawed and transferred into the uterus of the recipient ewe (receiving the embryo instead of the donor pregnant person), and three lambs were developed by "borrowing the abdomen". The success of long-term cryopreservation of embryos is a major breakthrough in embryo transfer technology, which provides convenience for expanding the use of embryo transfer technology. Embryo cryopreservation technology is the only reliable method to save the cost of livestock feeding tube, store genetic material and establish a national gene bank to preserve livestock breed resources for a long time.