Best, mean and worst results of toluidine blue staining in experimental group at 12 weeks. (A) The repair tissue (R) almost completely covered the cartilage defect flush with that of native cartilage (C). The thickness of the repair tissue was similar with that of the native tissue. At higher magnification (B), the demarcation between the repair tissue and the surrounding cartilage was almost undistinguishable. The repair tissue was well organized with nearly normal cell distribution. (C) The repair tissue (R) almost completely filled the cartilage defect. No fissures were observed. The repair tissue was thinner than adjacent healthy cartilage. At higher magnification (D), No clear clefs were observed between the repair tissue and the native cartilage, although the demarcation was still distinguishable. The organization of the repair tissue was poor. (E) Large cracks (arrow) were seen in the center of the repair tissue (R). At higher magnification (F), the integration between the repair tissue and the adjacent cartilage was good. The left column images are magnified 20X, and the right column images are magnified 100X.