Vitrification Study In Mouse Embryo

In the present study, mouse embryos (Day 3.5 – 4) collected from superovulated mice were frozen by open pulled straw (OPS) vitrification and conventionally frozen before in vitro culture. The objective was to assess embryo survival rate and process of embryo handling during commercial embryo transfer (ET) using the conventional freezing method as a comparison. The results as following: (1) During the vitrification of using different medium, the developed morulae were reached by 70.00% for medium TCM-199, and 72.34% for medium D-PBS. There were no significant difference between 2 mediums (p > 0.05); (2) The morphologically normal rates of thawed morulae and blastocysts with glass straw and open pulled straw as a carrier were 95.23% vs. 89.66% and 92.00% vs. 86.84%. Developing rates of thawed morulae and blastocysts were 87.57% vs. 86.40% and 85.83% vs. 77.14% (p > 0.05) respectively; (3) Morphologically normal rates of embryos vitrified or conventionally frozen were 97.78% vs. 94.64% at the morula stage, and 95.12% vs. 100%. The developing rates of embryos vitrified or conventionally frozen were 95.45% vs. 88.94% at the morulae stage, and 86.16% vs. 83.33% at the blastocysts stage respectively. No significant difference was found at the blastocysts stage between vitrified or conventionally frozen (p > 0.05), although significant difference was found at the morulae stage between vitrified or conventionally frozen (p < 0.05); (4) The morphologically normal rates of thawed embryos between OPS straw or 0.25ml straw at the stage of morulae were97.01% and 91.84%, 88.46% and 75.47% at the blastocysts stage. The developing rates of embryos vitrified with OPS and 0.25ml straw at the morula were 86.91% vs. 75.51%, at the blastocyst were 83.51% vs. 68.89% (p > 0.05) respectively. The study demonstrated about the same survival rates for vitrified and conventionally cryopreserved embryos of morulae and blastocysts stages during in vitro embryo culture. OPS vitrification is an effective and rapid method of cryopreservation of mouse embryos.