Is sucrose required in open pulled straw (OPS) vitrification of mouse embryos?

The study addresses the relevance of sucrose with OPS vitrification of murine blastocysts. In a 3 x 3 factorial experiment, blastocysts were subjected to vitrification solution (20% Me2SO and 20% EG) containing 0.0, 0.4 or 0.8M sucrose and warming solution (HEPES buffered TCM 199) containing 0.00, 0.25 or 0.50M sucrose. After 48h of in vitro culture, with 0.4 M sucrose in vitrification solution, 84-87% of embryos had reached the expanded blastocyst stage, as compared to 76-82% with 0.0M and 40-54% (P < 0.01) with 0.8M sucrose. Hatching rates confirmed the tendency. The sucrose content of the warming solution had no significant effect on expansion or hatching rates (P > 0.05). It may be concluded that, whereas, vitrification solution should contain a moderate concentration of sucrose, in dilution medium sucrose is dispensable. This implies that embryos may be transferred directly after warming, which, if applicable to farm animals, would greatly facilitate vitrification in practice.