Viabilidade e Fertilização in vitro de Oócitos Bovinos após Vitrificação Viability and in vitro Fertilization of Bovine Oocytes after Vitrification

ABSTRACT Purpose: to verify vitrification techniques using 6 M DMSOto cryopreserve in vitro matured bovine oocytes, and to assessthe effects of the time of exposure to vitrification solutions(VS). Methods: dilutions of VS were prepared from the stock VS(VS 100%) consisting of 6 M DMSO to give 25 and 65%DMSO solutions. Bovine oocytes were in vitro matured for18-22 h. Matured oocytes were placed first into 25% VS, atroom temperature for 5 min, then transferred to 65% VS,before being pipetted into the 100% VS in plastic straws.Three experimental groups were formed: in the first group,time of pipetting through 65% VS and loading the strawtook up to 60 s, in the second group it did not exceed 30 s.For thawing, straws were held in air for 10 s and then in awater bath for 10 s. The contents of each straw were expelledin sucrose solution and held for 5 min. In the thirdexperimental group, oocytes went through all VS, but werenot vitrified. All retrieved oocytes were inseminated. Forcontrol, fresh,