Embryos developmental capacity of vitrified 8-cell embryos in vitro or in vivo

Objective To observe the blastocyst formation rate,blastocyst hatching rate,embryo implantation rate,the birth rate of vitrified 8-cell embryos in mice compared with fresh 8-cell embryos and to evaluate the impact of vitrification on embryos developmental ability in vitro and in vivo.Methods A total of 106 females mice(6 to 7 weeks old) were used in this experiment.After 36 hours of culture,2-cell embryos were obtained and observed embryonic development.And 6-to 8-cell embryos were divided into fresh-embryo group(fresh embryo transfer),and vitrified-embryo group(vitrified embryos were stored for 2 weeks in liquid nitrogen,then thawed and transfer).Fifty pre-transferring embryos were cultured for 48 to 72 hours in vitro in each group.The numbers of blastocysts and hatched blastocysts were recorded.After 1 to 3 hours of culture from thawing,the morphologically normal 8-cell embryos were selected to transfer to each side of uterus in pseudopregnant mouse for 63 to 67 hours.Fresh transplantation group was transferred fresh 8-cell embryos.The number of live pups was recorded after 17 to 20 days of pregnancy by natural delivery.The pregnancy rate and birth rate were compared between two groups.Results The blastocyst formation rate,the blastocyst hatching rate,the pregnancy rate and the birth rate were 92%,84%,48.93% and 13.16% in fresh-embryo group and 90%,86%,47.06% and 12.62% in vitrified-embryo group,which showed no significant differences between two groups(P0.05).Conclusion Vitrification has less impact on the mice embryos developmental capacity in vitro and in vivo.