Best, mean and worst results of toluidine blue staining in control group at 12 weeks. (A) The cartilage defect was almost fully covered by repair tissue (R), but poor tuluidine blue staining was observed. At higher magnification (B), the demarcation between the repair tissue and the surrounding cartilage (C) was clear, although no clefs were observed. The organization of the repair tissue was poor with no typical cell distribution. (C) Clear crack or a poorly organized repair tissue (R) was observed in the defect. Subchondral bone formation was poor. At higher magnification (D), the integration was slight, and the organization of the repair tissue was poor with no typical cell distribution. (E) membrane-like and negatively stained repair tissue (R) covered the defect. At higher magnification (F), no integration was observed. No chondrocyte-like cells were seen. The left column images are magnified 20X, and the right column images are magnified 100X.