Effect of antioxidant on in-vitro maturation of vitrified bovine oocytes

The present study was undertaken to investigate the effect of alpha-tocopherol on in-vitro maturation of vitrified bovine oocytes. The cumulus-oocyte-complexes (COCs) recovered from follicles (3-5 mm diameter) by aspiration and slicing techniques were equally divided into 5 (five) groups consisting 66 COCs in each. The vitrified bovine oocytes were sub-grouped into control and treatment group. The vitrified-and non-vitrified-control group of oocytes were in-vitro matured in TCM-199 media without supplementation of vitamin E. In three vitrified treatment groups, the oocytes were in-vitro cultured in TCM-199 media supplemented with vitamin E (alpha-tocopherol) @ 50 mu M, 100 mu M and 200 mu M, respectively. The mean percentage of cumulus cell expansion and polar body formation in non-vitrified control and vitrified control groups were 85.18 +/- 2.57 and 65.38 +/- 1.83, and 51.67 +/- 1.94 and 30.26 +/- 0.16, respectively. The rate of cumulus cell expansion and polar body formation in the oocytes of three vitrified treatment groups media supplemented with vitamin E @ 50 mu M, 100 mu M and 200 mu M were 56.39 +/- 3.49 and 34.62 +/- 1.83, 69.95 +/- 3.20 and 56.23 +/- 1.61, and 54.44 +/- 4.73 and 31.62 +/- 4.50% respectively. Mean percentage of both cumulus cell expansion and polar body formation in the non-vitrified control group were significantly higher than that in the vitrified control group. In the treatment group supplemented with vitamin E @ 100 mu M, both cumulus cells expansion and polar body formation were significantly higher than that in media supplemented with 50 mu M and 200 mu M vitamin E as well as in vitrified control group.