Abstract: Aggregating diploid embryonic cells with tetraploid embryonic cells forms 2n/4n chimaeras.Tetraploid cells demonstrate a preferential distribution in chimaeras during embryonic development.Tetraploid cells are preferentially allocated to the extraembryonic tissues,such as placenta,rather than the fetus itself.This paper summarized methods of producing 2n/4n chimaeras,and developmental characteristics and possible applications of the chimaeras.