Cryosurvival after exposure of IVF-derived Nellore embryos to different cryoprotectants and exposure times during vitrification

We evaluated the effects of the vitrification solution (i.e., ethylene glycol (EG) + dimethyl sulfoxide (DMSO) with or without propylene glycol (PG)) and of exposure time on the re-expansion and hatching rates of vitrified Bos indicus embryos. In vitro produced embryos (n = 1050) were divided into seven groups: control group (non-vitrified embryos) and six vitrification groups with different cryoprotectant concentrations and exposure times. After vitrification, embryos were cultured for determination of re-expansion and hatching rates. Vitrification with 25% DMSO +25% EG (exposure for 1 min and 20 s) resulted in the highest re-expansion (65.2%) and hatching (68.2%) rates. The lowest re-expansion and hatching rates were observed in vitrification with 12.5% DMSO + 25% EG + 12.5% PG with both tested exposure times (i.e., 3 min + 1 min and 1 min + 20 s). A combination of DMSO + EG is efficient to preserve blastocysts, especially following a short exposure time.