Study On Vitrification Of Bovine Oocytes

The objective of this thesis was to investigate the vitrification of bovine oocytes in maiosis metaphaseⅡ(MⅡ) or germial vesicle(GV) stage.The results were shown as follows:Bovine MⅡoocytes were vitrified by Glass Micropipette(GMP) method and solid surface vitrification(SSV) method.The cleavage development rate did not have significantly different between GMP method(27.1%) and SSV method(32.6%) (P＞0.05),but SSV method(32.6%) was better than GMP method(27.1%).There were significant differences between treated groups and control group(P＜0.01).Bovine MⅡoocytes in treated and control groups were cultured by IVF method and parthenogenetic method.The blastocyst development rates did not have significantly different between SSV+IVF group(0.6%) and SSV+ parthenogenetic group(2.7%)(P＞0.05),but SSV+ parthenogenetic group(2.7%) was better than SSV+IVF group(0.6%).There were significant differences between treated groups and control groups(0.6%,2.7%vs 23.2%,22.7%,respectively,P＜0.01).Differernt concentrations of cytochalasin-B(CB) on the development of bovine matured oocytes following SSV were examined.These results demonstrated that:no significant differences were observed in the survival rate among the control and treatment groups(P＞0.05);However,after parthenogenetic of oocytes,vitrified oocytes treated with 20μg/ml CB resulted in a higher(47.67%vs 30.25%,respectively, P＜0.05)cleavage development rate than that of the control,while the blastocyst development rates were significantly higher(9.00%vs 1.75%,respectively,P≤0.01) than the control and other treatment groups(P＜0.05).In conclusion,the protective effects of CB depended on the concentration of CB in the vitrification process, especially pretreatment with 20μg/ml CB was beneficial for the vitrification of mature bovine oocytes.Differernt concentrations of cytochalasin B on the bovine GV-stage oocytes were examined.These results demonstrated that no significant differences were observed in vitro maturation rate among with or without CB pretreatment(P＞0.05), while they were all significantly lower than that in the IVM group.In conclusion, different concentration CB(2.5,7.5,15,20 and30μg/ml)treatments before vitrification did not improve the maturation rate following the vitrification of immature bovine oocytes.