Fig. 3

Representative safranin O-stained sections of articular cartilage. a In the control group, the cartilage surface was smooth and safranin O staining was uniform. b At 2 weeks after surgery, chondrocytes arranged at the surface area were uneven and the matrix was intact. c At 4 weeks after surgery, the intensity of proteoglycan staining decreased, whereas that of chondrocytes increased. d Irregular cartilage surface and chondrocyte disturbance were observed at 6 weeks after surgery. e Chondrocyte death and proteoglycan loss were observed at 8 weeks after surgery. f The extracellular matrix showed a loss in staining intensity; unequivocal dissipation of chondrocytes were observed at the lesion area at 10 weeks after surgery. Magnification × 10