IN-VITRO EVALUATION AND PREGNANCY RATES AFTER VITRIFICATION OF IN-VITRO PRODUCED BOVINE EMBRYOS

The efficacy of different vitrification solutions to cryopreserve in v itro-produced bovine blastocysts was evaluated based on in vitro devel opment of embryos in culture and on in vivo development of embryos tra nsferred into recipients. In the first experiment, 2 vitrification sol utions were compared: propylene glycol + glycerol (Pg+Gly) and ethylen e glycol + Ficoll + sucrose (EFS). Differences in the overall developm ent and hatching rates in favor of EFS were found (56.4 vs 33.3% and 3 5.4 vs 13.3 %; P<0.05). In the second experiment, 3 vitrification solu tions were compared: EFS, modified EFS (EFSm) and ethylene glycol + gl ycerol (Eg+Gly). The vitrification solutions EFSm and Eg+Gly yield hig her hatching rates than did EFS (57.7 vs 59.6 vs 35.7%; P<0.05). The l ast experiment was designed to compare in vivo 2 vitrification solutio ns: EFSm and Eg+Gly. There were no differences between them based on t he results obtained after transfer (35.2 vs 43.7%). The vitrification solutions EFSm and Eg+Gly have resulted in good pregnancy rates. These results demonstrated that vitrification can be used successfully in t he cryopreservation of in-vitro produced bovine embryos, and it might be considered for use in commercial programs. (C) 1998 by Elsevier Sci ence Inc.