摘要
Usually it is rather difficult to obtain and retain an ideal phenotype in an animal breeding program.Inspired by the success in transplanting cellular nuclei of amphibian and fish species since the 1950s,scientists began to believe in the possibility that cloned mammals could be acquired as well in the same way.Some 20 years prior to 1986 when the British biologist S.M.Willadson succeeded in breeding the first sheep by nuclear transplant,Prof.T.C.Tung (Tong Dizhou), a famous Chinese exper-
