Effects of PAM treatment on expression of RANKL and OPG in the cartilage and subchondral bone. (a–e) Immunohistochemical detection of RANKL expression in cartilage in Sham (a), ACLT (b,c) and PAM (d,e) samples, arrows point to positive cells. (f–j) OPG positive cells in the cartilage of the indicated samples. (k–o) RANKL positive cells in the subchondral bone samples. (p–t) OPG positive cells in the subchondral bone samples. Bar represents 100 μm.