DNA fragmentation of equine cumulus cells from Cumulus-Oocyte complexes submitted to vitrification and its relationship to the developmental competence of the oocyte.

The objectives of this study were to evaluate the effect of vitrification on the DNA fragmentation rate of equine cumulus cells and to assess its relationship to oocyte in vitro maturation (IVM) after vitrification. Cumulus cells (CC) from 14 mares were recovered from COCs, previously submitted to vitrification (VIT) and IVM. The DNA fragmentation rate of the cumulus cells (CC-DF) was assessed using a chromatin dispersion test. CC-DF rates between vitrified and control COCs were statistically compared by Student's t-test. The rates of CC-DF from control COCs were lower than in vitrified COCs. The percentage of CC-DF was not significantly different (p > .05) between groups of COCs able to reach metaphase II (MII > 0) and those in which oocyte maturation was not achieved (MII = 0). In conclusion, vitrification has a deleterious effect on the DNA fragmentation of equine cumulus cells; however, this parameter cannot be used as a predictor for IVM success after COCs vitrification.