Vitrification of Porcine In Vitro‐Produced Embryos at the Pronuclear and Blastocyst Stages Using Ampholytic Polymer Compounds as Cryoprotective Agents

Porcine in vitro-produced embryos at the pronuclear or blastocyst stage were vitrified by the Cryotop method with different concentrations of carboxylated poly-L-lysine (CPLL) or 3,3-dimethylglutaric anhydride poly-L-lysine (DMGA-PLL) to determine the efficacy of these ampholytic polymer compounds as cryoprotective agents (CPAs). The concentration of CPLL or DMGA-PLL in the vitrification solution had a significant effect on the viability of vitrified-warmed blastocysts and expanded blastocysts, with the highest survival rates at 10% (v/v). When blastocysts and expanded blastocysts were vitrified with or without 10% CPLL or DMGA-PLL, there were significant differences in the survival rates after warming among the different supplements, with the highest rates obtained when 10% DMGA-PLL was added. The concentration of CPLL or DMGA-PLL in the vitrification solution did not affect the viability of vitrified-warmed pronuclear stage embryos, but the addition of 10% CPLL or DMGA-PLL improved the cleavage and blastocyst formation rates following in vitro culture. Furthermore, embryos vitrified with 10% DMGA-PLL had similar in vitro developmental potential as nonvitrified embryos. The results showed the usefulness of ampholytic polymer compounds, especially DMGA-PLL, as CPAs in the vitrification of porcine embryos at the pronuclear and blastocyst stages.