Addition of Alpha-Tocopherol to Culture Medium Improves the Quality and Cryosurvival of Nuclear-Transferred Ovine Embryos

Abstract

The aim of this study was to reconstruct and cryopreserve somatic cell nuclear transferred (SCNT) ovine embryos and evaluate the effect of α-tocopherol on blastocyst development and subsequent cryosurvival of the SCNT embryos. The α-tocopherol (100 μg/ml) was added into culture medium for the SCNT embryos, the yield and total cell numbers of blastocysts were determined and the apoptosis incidences of the blastocysts were evaluated using the TUNEL assay. The blastocysts from the α-tocopherol and untreated groups were then frozen-thawed, and their cryosurvival was assessed by in vitro culture for 48 h. The results showed that there were no significant differences in blastocyst yield (26.3 vs. 22.3%) and total cell number (68.2 vs. 64.3) between the α-tocopherol and untreated groups. However, addition of α-tocopherol to the culture medium significantly decreased the apoptotic cell number (3.4 vs. 5.5) and significantly increased the cryosurvival of SCNT blastocysts (66.8 vs. 50.7%). In conclusion, addition of α-tocopherol to SCNT embryo culture medium was beneficial for improving embryo quality by decreasing the apoptotic blastocyst cell number and improving the tolerance of the embryos to cryopreservation.