Comparison of two vitrification methods for cryopreservation of porcine embryos
Riha, J.(Vyzkumny Ustav pro Chov Skotu, Rapotin (Czech Republic))E-mail:jan.riha@vuchs.cz | Vejnar, J.(Vyzkumny Ustav Zivocisne Vyroby, Kostelec nad Orlici (Czech Republic))
The aim of this study was to compare two vitrification methods of porcine perihatching blastocysts with regard to the success of transfer of these embryos to the recipients. Expanded, hatching, or hatched blastocysts were recovered post mortem from superovulated donors in 5.5 to 6.0 days. In protocol VS I, the embryos in perihatching developmental stage were equilibrated in a culture medium H-MEMD with 10% v/v of glycerol (1.37M solution of glycerol in medium) for 10 min and placed in a vitrification medium for 1.5 min max. (vitrification medium contained 50% v/v 2M sucrose in tridistilled water, 30% v/v of glycerol, and 20% v/v of foetal calf serum - FCS). For protocol VS II, we used H-MEMD culture medium supplemented with 20% v/v of FCS, 25% v/v ethylene glycol, and 25% v/v dimethyl sulphoxide (DMSO). Embryos were equilibrated for 10 min in a mixture of the vitrification medium and culture medium (1 : 1), and were kept in the vitrification medium for 1.5 minutes. Both types of embryos were then dropped with micropipette and stored in liquid nitrogen vapour. They were thawed by immersing the drop with the embryo in H-MEMD culture medium with 0.8M sucrose for 10 minutes. After thawing and washing in the medium with sucrose, all embryos were washed three times in a fresh medium and prepared for transfer. Recipients were synchronized either using Regumate-feeding followed by treatment with PMSG and HCG (gilts) or using piglet weaning (sows - 1st and 2nd parity). The fraction of viable embryo vitrified under VS I or VS II protocol was 85% and 80%, respectively, in comparison with 95% in control fresh embryos (P more than 0.05). Pregnancy of recipients was 57.3% (5/7), 67.0% (4/6) for VS I or VS II group and 42.7% (10/23) for control (P less than 0.001). We can conclude that both protocols for vitrification yielded similar results and can be used for cryopreservation of porcine embryos.
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