Fig. 2From: The expression of SIRT1 in articular cartilage of patients with knee osteoarthritis and its correlation with disease severityThe upper image was visualized with H&E staining of the cartilage (×100), the middle image was visualized with safranin-O-fast green staining (×100), and the lower image was visualized with SIRT1 immunohistochemical staining (×400). a Normal group. b Mild OA group. c Moderate OA group. d Severe OA groupBack to article page