The colony formation of bone marrow-derived stem cells(BMSCs)and meniscus-derived stem cells(MMSCs).A. Colonies of BMSCs. B. Colonies of MMSCs. C. A sample colony of BMSCs. D. A sample colony of MMSCs. E. Quantitative analysis of colonies formed by BMSCs and MMSCs. The colonies were detected by staining with Methyl violet at 15 days primary culture. Cell numbers were counted after trypsinized from each colony respectively. Colony number of MMSCs was significantly different from that of BMSCs (*p < 0.05). (Bars: 50 μm).