Abstract: Objective To investigate the effects of different concentrations of cytochalasin B (CB) on the reconstruction of egg cytoskeleton and embryo development after oocyte spindle transplantation in mice, and to screen out the better CB concentration. 
Methods Eight-week-old C57BL/6 female mouse eggs were transplanted using conventional, low, medium, and high doses of CB. The efficiency of spindle transplantation in mice was measured. The fertilization rate of in vitro fertiliazation (IVF), cleavage rate, blastocyst rate and hatching rate of reconstructed mouse eggs were calculated. The blastocysts of each group were stained by immunofluorescence and calculated by fluorescence microscope. Mouse eggs were reconstructed and stained with immunofluorescence. The cytoskeleton was observed and analyzed by confocal microscopy. 
Results ①Compared with the conventional group, there was no difference in the efficiency of spindle transplantation in the low dose, medium dose and high dose groups (P＞0.05). ②The fertilization rate of high dose group was lower than that of conventional group (P＜0.05), and the blastocyst rate and hatching rate of high dose group were lower than those of conventional group and medium dose group (P＜0.05). ③The total number of blastocyst cells in the high dose group was less than that in the conventional group (P＜0.05), and the total number of blastocyst cells in the medium dose group was more than that in the conventional group (P＜0.05). ④Compared with the conventional group, there was no difference in the positive ratio of microfilaments of reconstructed mice eggs in low-dose, medium-dose, high-dose groups at different time points (P>0.05). The average optical density values of microfilaments in different time groups were different (P< 0.05), there were significant differences between time points (P<0.05), and the time variation trend was different among groups (P<0.05). That is, different concentrations of CB and different observation time had significant effects on the recovery of reconstructed egg cytoskeleton in mice, and there were significant differences. 
Conclusion In the concentration range of CB selected in this study, the medium dose group was better than the conventional group.

Key words: spindle apparatus, transplantation, embryonic development ,