In vitro maturation medium supplementation with resveratrol improves cumulus cell expansion and developmental competence of Sanjabi sheep oocytes

The purpose of this study was to evaluate the effect of different concentrations of resveratrol (0, 0.1, 0.25, 0.5, 2.0, and 5.0 mu M) which was added to the IVM medium on cumulus expansion, nuclear maturation, and total cell number of embryos in Sanjabi ewes. Meiotic progression was evaluated based on cumulus expansion, the frequency of germinal vesicles, germinal vesicle breakdown and metaphase II (MII). The effects of the resveratrol concentrations in the IVM medium on cleavage and developmental potential to blastocyst stage were also investigated. After maturation, a sample of oocytes were fixed and stained to evaluate nuclear maturation, while the remaining oocytes were fertilized in vitro with fresh semen, then cultured for 8 days in synthetic oviductal fluid (SOF) medium for assessment of oocyte developmental capacity. Addition of 0.25 and 0.5 mu M of resveratrol to the maturation medium was shown to significantly increase cumulus expansion (P < 0.05). There was no significant difference in the percentage of MII oocytes between control, and 0.1, 0.25, 0.5 and 2.0 mu M resveratrol treatment groups. Furthermore, addition of 0.25 and 0.5 mu M of resveratrol to IVM medium also significantly improved blastocyst formation, and addition of 0.5 mu M resveratrol in maturation media increased trophectoderm cell numbers, inner cell mass and the total cell number of ovine embryos. However, addition of high resveratrol concentrations (5.0 mu M) to IVM medium had a negative effect on the maturation rate and blastocyst formation. Together, these findings show that supplementation of IVM medium with 0.25 and 0.5 mu M resveratrol can improve the meiotic competence and early embryonic development of Sanjabi sheep oocytes.