Effects of different cryoprotectants and cryopreservation protocols on the development of 2-4 cell mouse embryos

This study evaluated the effects of different cryoprotectants and cryopreservation protocols on the development of in vivo fertilized 2-4 cell mouse embryos. Mouse embryos were cryopreserved by using propylene glycerol (PG), ethylene glycerol (EG), dimethyl sulfoxide (DMSO) or glycerol (G) as cryoprotectant with slow-freezing or Vit-Master vitrification protocol. After thawing, the survival rate, blastocyst formation rate and blastocyst hatching rate of the embryos were compared. When mouse embryos were cryopreserved by the slow-freezing, survival rate, blastocyst formation rate and blastocyst hatching rate of the embryos with PG were significantly higher than those of DMSO and G (P < 0.05, respectively), but there is no significantly difference among those of DMSO, G and EG(p > 0.05), and between PG and EG. When mouse embryos were cryopreserved by Vit-Master vitrification, survival rate, blastocyst formation rate and blastocyst hatching rate of the embryos with EG were significantly higher than those of PG, DMSO and G (P < 0.05). There were no significant differences among those of PG, DMSO and G (p > 0.05). In conclusion, PG was the optimal cryoprotectant for the cryopreservation of 2-4 cell mouse embryos by slow-freezing protocol. EG was the optimal cryoprotectant for the cryopresevation of 2-4 cell mouse embryos by Vit-Master vitrification protocol, which may be commonly used in clinical and laboratory practice.