The aim of this study was to determine the effect of dimethylformamide (DF) associated with ethylene glycol (EG) or 1-2 propanediol (PROH) during vitrification, on the in vitro development of mouse blastocysts. Cryoprotectant toxicity was evaluated exposing embryos into three different equilibrium solutions (ES) composed by DF, EG or PROH mixtures (10% v/v of each) in mPBS + 0.5% PVA at different interval times (1, 3 and 10min). In a second experiment, embryos were exposed to the same ES (either 1 or 3min), following for the three respectively vitrification solutions (VS) (20% v/v of each) for 30s. After 72 hours of in vitro culture, embryo hatching and expansion rates were similar for the ES1 and ES2 equilibration solutions during the time interval of 1 or 3min. However embryos exposed for 10 min to the DF equilibration solutions, had lower survival rates than EG-PROH solution (P<0.01). Furthermore, survival rates for embryos exposed to DF-PROH (ES+VS) were lower than embryos exposed to the other solutions (P<0.01). Blastocyst vitrification was performed with the three ES+VS (for 1min and 30s, respectively), using glass micropipettes (GMP). Survival rates were lower for blastocysts vitrified with DF solutions (3%-3/108 and 17.1%-19/111) (P<0.01) than with PROH+EG vitrification solutions (69%-73/105). In conclusion, DF as a cryoprotectant into vitrification solutions have deleterious effects on the in vitro developmental competence of vitrified mouse blastocysts.
mouse; blastocyst; vitrification; dimethylformamide; glass micro pipettes
