Developmental competence of bovine embryos reconstructed by the transfer of somatic cells derived from frozen tissues

The ability of frozen-thawed fetal skin was examined to generate viable cel l lines for nuclear transfer. Fetal skin frozen at -35 degreesC or -80 degr eesC in the presence of 5% DMSO were used as tissue explants to generate so matic cells. The resultant confluent cells were then used as donors for nuc lear transfer (NT). Of the bovine NT embryos reconstructed from the somatic cells, 78% to 81% showed cleavage, 43% to 48% reached the stage of morula formation and 34% to 35% reached blastocyst formation. There were no signif icant differences in development (P > 0.05) when the NT embryos were compar ed with those reconstructed from fresh somatic-cell-derived skin tissues (7 5%. 45%, and 38%. for cleavage, and development to morula and blastocyst st ages, respectively). The results indicated that cell lines derived from bov ine fetal skin cryopreserved by a simple method could be used as donors in nuclear transfer, The resulting embryos showed similar development in vitro to those reconstructed from unfrozen fetal-skin-derived somatic cells.