The open pulled straw vitrification of ovine GV-oocytes: Positive effect of rapid cooling or rapid thawing or both?

Three protocols for the open pulled straw (OPS) vitrification of ovine GV-o ocytes with slow cooling-rapid thawing, rapid cooling-slow thawing, and rap id cooling-rapid thawing were tested. The effect of ultra-rapid cooling in liquid nitrogen slush and superfine open pulled straws (SOPS) was also stud ied. Our results prove that both rapid cooling and rapid thawing are contri buting in improved results achieved with the OPS technology. The use of liq uid nitrogen slush is beneficial for ovine GV stage oocyte nitrification.