Abstract: Objective To identify the source of the somatic cell nuclear transfer blastocysts , microsatellite DNA assay was developed. Methods DNA isolation from SCNT blastocyst，donor BALB/c mouse, recipient C57BL/6 mouse and KM mouse are tested by nested polymerase-chainreaction(PCR) analysis. Primers designed for four specific microsatellite locus(D3Mit28, D11Mit258, D12Mit136, D14Mit50)were employed. The amplified PCR products from the final reaction was analyzed by agarose gel electrophoresis and visualized with ethidium bromide staining. Results Amplification of genomic material by nest PCR represents the most sensitive method for the detection and might be detected successfully even though very low DNA copies. Microsatellite DNA analyses examining four loci confirm that all the SCNT blastocysts were genetically identical to the donor mouse. Additionally, the SCNT embryos are not genetically related to the respective recipient mouse. Furthermore sequences of SCNT blastocysts are diferent from the control KM mouse. Conclusion Our results prove that the nucleus of somatic cell nuclear transfer blastocysts come from somatic nucleus of donor BALB/c mouse.

Key words: cell nuclear/transfer, disease model, microsatellite DNA, Identification