The effect of cryodevice and cryoprotectant concentration on buffalo oocytes vitrified at MII stage
Mahmound, K Gh MEl-Sokary, M M MScholkamy, T HAbou El-Roos, M E ASosa, G A MNawito, M
Vitrification is a common method for cryopreservation of gametes and embryos. Although successful oocyte vitrification has been achieved in several animal species, subsequent progress is still limited especially in buffalo. To improve the effectiveness of vitrification of buffalo oocytes, two experiments were conducted. The first experiment evaluated the effect of cryodevices on viability and maturation of vitrified, matured buffalo oocytes. The in vitro matured oocytes were divided into two groups, the first was vitrified using conventional French straws, while the other was vitrified using Cryotops. There was a significant reduction in the morphologically normal oocytes after vitrification with both methods. Maturation rates of vitrified thawed buffalo oocytes were significantly higher in Cryotops than straws. The survival rate after vitrification was similar for both straws and Cryotops. The percentages of viable oocytes were significantly lower in straw than in controls. The second experiment evaluated the effect of two concentrations of cryoprotectants on the vitrification of in vitro matured buffalo oocytes. Mixtures of DMSO and EG as cryoprotectant (CPA) solutions were prepared in TCM-199 with two concentrations of cryoprotectants. The first concentration was 6 M V2 (3 M E.G + 3 M DMSO), and the second concentration was 7 M V2 (3.5 M DMSO + 3.5 M EG). Each concentration of cryoprotectants was added in two steps, with the first step having half the concentration of the second (and final) concentration. The survival rate after vitrification was similar for both concentration (6 M and 7 M) groups. The maturation rates of vitrified thawed buffalo oocytes were significantly higher in 7 M concentration than in the 6 M group. In conclusion, the survivability and meiotic competence of buffalo oocytes improved with vitrification at higher concentration of cryoprotectants and using cryotops.(AU)
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