Effect of vitrification medium composition and exposure time on post-thaw development of buffalo embryos produced in vitro

This study examined the effects of different vitrification medium compositions and exposure times (2, 4 and 6 min) on the post-thaw development of buffalo embryos produced in vitro (IVP). The compositions were (1) 40% ethylene glycol (EG); (2) 25% glycerol (G) + 25% EG, and (3) 25% EG + 25% dimethylsulfoxide (DMSO). The base medium was 25 mM Hepes-buffered TCM-199 + 10% steer serum +50 μg/mL gentamycin. The IVP embryos were cryopreserved by a two-step vitrification method at 24 °C. After warming, the embryos were cultured in vitro for 72 h.The vitrification of morulae and blastocysts in 25% EG + 25% DMSO with an exposure time of 2 and 4 min, respectively, resulted in a better hatching rate than other combinations. The hatching rate of morulae vitrified in 25% EG + 25% G, 25% EG + 25% DMSO, and blastocysts vitrified in 40% EG, 25% EG + 25% DMSO were negatively correlated with exposure time. However, the hatching rate of blastocysts vitrified in 25% EG + 25% G was positively correlated with exposure time. The study demonstrated that the post-thaw in vitro development of IVP buffalo embryos was affected by the vitrification medium composition and exposure time.