The Effect of the Reduction of Volume of Blastocoel Cavity before Vitrification on Viability and Quality of In Vitro Mouse Blastocyst through Assessment of Fgf4 Gene Expression

Although studies have shown that viability rate of transferred blastocysts in comparison to embryos in previous stages is higher, the viability rate of warmed blastocysts was lower than embryos in other stages. This can be attributed to the present of fluid filled blastocoel cavity and potential risk of ice crystal formation. Moreover, the fluid can serve as an isolator against penetration of cryoprotectant agents (CPAs) to the embryos. In the present study by applying artificial collapse (AC) on blastocysts, we aimed to evaluate the effect of reduced volume of blastocoele fluid prior to vitrification on the quality of warmed in vitro mice embryos. In this regards, quantity of Fgf4 gene expression, viability and hatching rates were considered. Mouse blastocysts divided into 3 groups including: A) Vitrified-thawed blastocysts after artificial collapse, B) Vitrified-thawed blastocysts, C) Fresh blastocysts as a control group. The survival and hatching rate of embryos were evaluated by SPSS and one way ANOVA with post hoc Duncan test and the expression of Fgf4 gene was assessed by Real Time PCR technique in comparison to control group. Artificial collapse improved the rate of zona pellucida hatching showed a significant increase (p<0.05). Moreover, the level of Fgf4 gene expression in the AC group increased significantly (p<0.05) in comparison to the control group. It can be concluded that artificial collapse of blastocyst could be effective way to improve the implantation rate.