Abstract: Fibroblasts were isolated from adult mouse lip skin and cultured，and then starved 1 week with 0.5% FBS media before used as donor cells. In addition, adult female mice were superovulated with PMSG and hCG, and their eggs were taken as recipients. Embryos reconstructed were activated 6 hours with 10 mmol/L SrCl₂ 2 hours after injected nucleus, and then cocultured with mouse oviduct epidermal cells, adding M16 media modified. When being in the stage of blastocyst, they were transfered on the feeder layers of mouse embryonic fibroblasts, adding rat cardiomyocyte media conditioned. After hatched from blastocysts, ICM were isolated and trypsinized, and then co-cultured continuously to gain ES cell masses. Results indicated that 2-cell rate of embryos reconstructed with fibroblasts was 54.05%, development rate of morula was 17.14%, blastocyst rate was 6.90%. Under the same circumstance, 2-cell rate of embryos reconstructed with cumulus cells was 60.00%, development rate of morula was 21.85%, blastocyst rate was 11.69 %, but developmental capacity of embryo reconstructed was no difference between two donor cells. ES cell -like colonies were isolated from 6 blastocysts with fibroblasts, in which 3 ES cell-like colonies could be passaged and cultured successfully. In control group ES cell-like colonies were harvested from 9 blastocysts, in which 5 ES cell-like colonies could be passaged successfully. ES cells isolated were island-like, positive by AKP staining, and could spontaneously differentiate into epidermal or shuttle-like cells around them in vitro. After routinely frozen and thawed, they were with characteristics of ES cell.