Document Type : Original Article
EMBRIOLOGY DEPARTMENT, ROYAN INSTITUTE, TEHRAN, IRAN
Introduction: This Study was designed to compare the effects of three vitrification procedures [conventional (C), open pulled straw (OPS) and closed pulled straw (CPS)] on morphological survival of two-cell mouse embryos and their subsequent development to hatched blastocysts.
Material and Methods: Two-cell mouse embryos were divided into four groups, control (194), OPS (150), CPS (155) and C (160). The control embryos were cultured in HTF, for 96-120hrs. Embryos in vitrification group were vitrified with 5.5M EG and 1M sucrose by three different methods. After rapidly thawing at room temperature, embryos were diluted in stepwise sucrose solution (0.5, 0.25 and 0.125). The embryos were rinsed 3 times in HTF methods, then cultured. Survival of embryos in each procedure was determined after thawing. Ability of the survived embryos to continue development was assessed upon subsequent culture in vitro and compared with control group. All of the results were analyzed by chi-square test.
Results: The survival rate of the embryos after thawing was significantly higher in CPS (76%) compared to OPS(62%) (P<0.01) and C(66%), (P<0.05). The rate of hatched blastocyst didn’t differ significantly for C (58%), OPS (55%) and CPS (64%), but was significantly lower than control (72%) for C(P<0.05) and OPS (P<0.01).
Conclusion: This Study revealed that the CPS method seems to be a usful procedure for cryopreservation of two-cell mouse embryo.