In the present study, effects of concentration of cryoprotectant solutions on the nuclear maturation of vitrifiedthawed bovine oocytes were examined. Also, the developmental capacity of vitrified-thawed immature oocytes following ICSI was investigated. Oocytes were cultured in TCM-199 medium supplemented with 5% FBS at C in 5% and air. The in vitro maturation rate of vitrified oocytes was 24.5 4.2%. The in vitro maturation rate of vitrified oocytes was lower than that of the control (72.0 3.5%, p<0.05). The in vitro maturation rate of vitrifiedthawed oocytes incubated in TCM-199 medium supplemented with 1.05.0 ug CB were 26.7 3.2%, 35.7 3.2%, 54.0 3.0%, 42.5 3.6%, respectively. The in vitro maturation rate (57.0 3.0%) of the vitrified-thawed oocytes treated with 3.0 g CB for 20 min was the highest of all vitrification groups, although the maturation rate were significantly (p<0.05) lower than those of fresh oocytes. The in vitro maturation rates of the vitrified-thawed (with EDS and EDT) oocytes were 53.8 3.4%, 51.1 3.5%, respectively. This results were lower than the control group (72.0 3.0%). The in vitro developmental rates of the vitrified-thawed oocytes following ICSI were 28.6 4.5%, 25.6 4.3%, respectively. This results were lower than the control group (40.0 4.0%).

• Kim, Sang-Keun
• Rhee, Man-Hee
• Park, Ji-Hoon