Improvement of cortical granules migration andin vitro embryo production of vitrified bovine oocyte by 9-cis retinoic acid

Objective:To reveal the effects of 9-cis retinoic acid (RA) on cortical granules (CGs) migration andin vitro embryo production (IVP) rate in meiosisⅡvitrified bovine oocyte. Methods:Followingin vitro maturation (IVM) in a medium containing 5 nM of 9-cis-RA, 60 oocytes were vitrified and then thawed. Then, half of them were evaluated for CGs migration and the other half were used for in vitro fertilization and IVP (on day 3). In addition, the other 60 oocytes were considered as the control group, which did not receive RA in IVM medium. The data were presented to one way analysis of variance (ANOVA) and Duncan's test.Results:Results showed that IVP rate (4-8 cells embryos) was significantly (P<0.05) higher than the control group when RA had been added to IVM medium. Furthermore, the presence of RA in IVM medium improved the rate and mode of CGs migration so that the rate of oocytes that had completed CGs migration in the group, which had received RA, was significantly higher than the control group.Conclusions:This study shows that presence of RA in IVM medium enhances the developmental competence and CGs distribution of meiosisⅡvitrified bovine oocyte. Therefore, adding RA in IVM medium can decrease the ultrastructural changes during vitrification and can improve the efficiency of bovine oocyte vitrification.