Introduction: The cryopreservation of embryos has become an integral part of ART. The aim of this study was evaluating the necrotic blastomere removal effect on vitrified –warmed 4-cell stage mouse embryos development.
Materials and Methods: The retrieved 2-cell mouse embryos were cultured in G1TM ver3 medium until the 4-cell stage, then the embryos were vitrified with pretreatment and vitrification solutions. After warming the embryos were transferred to G1TM ver3 medium, and divided into intact (control) and partially (25%, 50% and 75%) damaged groups. In the partially damaged groups, the necrotic blastomeres were removed after zona pllucida laser hatching and embryos of two groups (control and removal) after reached to 8-cell stage were cultured for additional two days into G2TM ver3 medium. Finally, the rate of blastocyst formation, number of total blastomeres, number of blastomeres in each part of the inner cell mass (ICM) and trophoectoderm (TE) and apoptotic cells were compared statistically using c 2 and ANOVA tests. Results: The blastocyst formation was increased in all partially damaged groups after removal of necrotic blastomeres. This increase was only significantly (p