ABSTRACT
Objective: re-vitrification of embryos immediately after thawing or after a culture period could be used to preserve the extra embryos after embryo transfer. This study aims to clarify the effect of re-vitrification on Bax and Bcl-2 gene expressions of compact and early blastocyst stage embryos
Materials and Methods: this experimental study was performed on mouse embryos. We collected 8-cell stage embryos [n=400] from female mature mice, 60-62 hoursafter injection of human chorionic gonadotropin [hCG]. The embryos were divided into 5 groups: fresh [n=80], vitrified at the 8-cell stage [n=80], vitrified at the blastocyst stage [n=80], vitrified at the 8-cell stage, and re-vitrified at the compact [n=80] and early blastocyst stages [n=80]. Embryos were vitrified by cryolock. We analyzed the developmental rates of the vitrified-warmed embryos with the chi-square test. Quantitative polymerase chain reaction [qPCR] data were analyzed with SPSS version 16 using one-way analysis of variance [ANOVA] followed by Tukey's post hoc test. P<0.05 were considered statistically significant
Results: the expanded blastocyst formation rate showed a significant difference in re-vitrified embryos compared with fresh embryos [P<0.05]. However, this result was similar between the two re-vitrified groups. Our data showed a significant difference in expression of the Bax and Bcl-2 genes between re-vitrified and fresh embryos [P<0.05]. Expressions of the Bax and Bcl-2 genes showed no significant difference between the two re-vitrified groups
Conclusion: based on our study, re-vitrification could affect developmental rate and expressions of the Bax and Bcl2 genes