Effects of Vitrification on the Distribution of Cortical Granules and Developmental Competence of Matured Porcine Oocytes after Parthenogenetic Activation

This study was designed to investiga te the effects of vitrification on cortical granulesdistribution of in vitro matured porcine oocytes and evaluate their embryonic developmental competence after parthenogenetic activation.Two kinds of vitrification solution EDF40 and EDFS40 were used.Oocytes were randomly divided into three groups: control group,toxicity groups,vitrification groups.Part of treated oocytes were stained to observe the distribution of cortical granules.The rest were cultured in vitro to assess their developmental competence after parthenogenetic activation.The results showed that there were no significant differences in proportion of cortical granules partially release distribution and fully release distribution between toxicity groups and vitrification groups,but their proportions were significantly higher than that in control group(P 0.05).There were no significant differences between different toxicity groups or vitrification groups.The proportions of cortical granule distributed in the cortex in vitrification groups were significantly lower than that in toxicity groups(P0.05).The viability rates,cleavage rages and blastocyst rates in EFS40 toxicity group were significantly higher than EDFS40 toxicity group(86.6% vs.75.0%),(61.8% vs.40.7%),(30.2% vs.23.5%)(P 0.05).The viability rates of EFS40 vitrification group was significantly higher than those of EDFS40 vitrification group,but they were both significantly lower than that in the control group.In conclusion,cryoprotectants and vitrification lead to the release of cortical granules of porcine oocytes,EFS40 is more suitable than EDFS40 for cryopreservation in vitro matured porcine oocytes.