Vitrification of porcine embryos at various developmental stages using different ultra-rapid cooling procedures.

Abstract In this study, three different vitrification systems (open pulled straw: OPS; superfine open pulled straw: SOPS; and Vit-Master ® technology using SOPS: Vit-Master-SOPS) were compared in order to investigate the influence of cooling rate on in vitro development of vitrified/warmed porcine morulae, early blastocysts, or expanded blastocysts. Embryos were obtained surgically on Day 6 of the estrous cycle (D0=onset of estrus) from weaned crossbred sows, classified and pooled according their developmental stage. A subset of embryos from each developmental stage was cultured to evaluate the in vitro development of fresh embryos; the remaining embryos were randomly allocated to each vitrification system. After vitrification and warming, embryos were cultured in vitro for 96 h in TCM199 with 10% fetal calf serum at 39 °C, in 5% CO 2 in humidified air. During the culture period, embryos were morphologically evaluated for their developmental progression. The developmental stage of embryos at collection affected the survival and hatching rates of vitrified/warmed embryos ( P P >0.05). Vitrified expanded blastocysts showed the best development in vitro ( P