Abstract: To Study in vitro maturation of GV stage oocytes from ovaries of pubertal mice,and compared their fertilization,embryo development with those in vivo matured，mechanical isolation GV stage and in vivo matured oocytes from pubertal mice. GV stage oocytes were cultured in the solution consisted of α-MEM+1mg/ml Fetuin + 10% FCS+1.5 IU/ml rHCG ±5 ng/ml rEGF,16h later were transferd to f-HTF+10% FCS for 4h for IVF，tlien cultured in M16+10% FCS for 72 h, recording maturation, fertilization and cleavage, and compared with oocytes in vivo matured. Results：The maturation rate of GV stage oocyte is 89. 68%. Further supplementation of rEGF was not significantly increased the maturation rate of GV oocytes （P＞0.05），but the rate of fertilization, cleavage were significantly increased（P＜0.05）.The rate of fertilization and cleavage of in vivo matured oocyte was 62.83% and 60. 18%. However,the rate of fertilization and cleavage of in vitro matured oocyte was only 48.92% and 36. 69%，still lower than oocytes in vivo matured （P＜0.01）. Conclusions：GV stage oocyte of mice can be in vitro matured,fertil-ized,and cleavaged. Supplement the culture medium with Gn and rEGF promote the development potential of GV stage oocytes. However, the capacity of development of in vitro matured oocytes was lower than in vivo matured oocytes,indicating the culture system still need to be improved.

Key words: Immature mice oocytes, In-vitro maturation, Fertilization, Embryo development