Biphasic expression of sclerostin in calcified cartilage of mice with osteoarthritis. (A) Safranin O stains show the progression of cartilage lesions in the tibial plateau of osteoarthritis (OA) mice. Bar, 100 nm. (B) Immunostaining of sclerostin in calcified cartilage is shown. Bar, 100 nm. (C) Percentages of sclerostin-positive cells in calcified cartilage of the tibial plateau and internal femoral condyle. (D) Immunostaining of sclerostin in newly formed osteophytes in the tibial plateau. Bar, 100 nm. Enlarged image bar, 40 nm. Data are mean ± SEM. *P < 0.05 versus baseline (n = 7 animals per time point).