Cryopreservation of in vitro–produced sheep embryos: Effects of different protocols of lipid reduction

Abstract The low survival of sheep in vitro –produced (IVP) embryos after cryopreservation is a key limiting step to the widespread of this technology. In the present work, different approaches for enhancing cryosurvival of these embryos were compared: embryo delipidation by centrifugation in the absence or presence of cytochalasin D, a cytoskeleton stabilizer or by embryo culture in the presence of different doses of the trans -10 cis -12–conjugated linoleic acid isomer (CLA). Three experiments were conducted. In experiment 1, IVP blastocysts before vitrification were randomly distributed into four groups: control; centrifuged (cent), cytochalasin D (cyto-D), centrifuged + cytochalasin D (cent + cyto-D). In experiment 2, different doses of CLA (25, 50, and 100 μM) were supplemented during embryo culture before vitrification of blastocysts. A control group ran simultaneously. A third experiment was performed to compare both approaches from the previous ones but without the groups with the worst results (groups: control, cyto-D, cent + cyto-D, CLA25, CLA50). In all experiments, embryos integrity and reexpansion were assessed after warming and after 3 hours of culture. In experiment 1, the postwarming integrity rate was the lowest (P