The achievements of in vitro maturation after warming to the cryopreserved bovine oocytes by different vitrification methods

The susceptibility of bovine oocytes to freezing damage highlights the need to develop a vitrification methodology that will reduce cryosensitivity. This study was conducted to use two different vitrification methods to cryopreservation of immature oocytes and then examine how they affect the maturation success. The methods were used are Open Pulled Straw (OPS) and Solid Surface Vitrification (SSV). Immature oocytes were aspirated from the follicles on the ovaries of slaughtered bovines from a local abattoir were investigated under a stereomicroscope and 450 immature oocytes that had at least three layers of compacted cumulus cells were selected for this study. Three different groups (OPS, SSV and Control), that each consists of 150 oocytes were formed. Oocytes in the OPS and SSV groups were incubated for maturation after vitrification-warming, while oocytes in the control group were incubated for maturation non-vitrified. After maturation, oocytes were examined for the cumulus expansion and presence of polar body. When the polar body in oocytes stripped from the cumulus cells were examined, the polar body 23.19% (32/138) in the OPS group, 20.90% (28/134) in the SSV group, and 78.83% (108/137) oocyte in the control group were determined. The difference between OPS and SSV groups was not statistically significant (p>0.05). However, the results of control group was significantly higher than the vitrification groups (p