Fig. 4

ATF6-knockout mice have normal articular cartilage and develop OA following DMM at the same rate as wild-type controls. a Representative images of safranin O-stained sections from knee joints of 6–7-month-old ATF6α-knockout mice (n = 3) showing intact articular cartilage with no signs of degeneration. b Safranin O-stained sections of non-operated (left) and DMM-operated (right) knee joints from wild-type (WT; n = 7) and ATF6α KO (KO; n = 9) mice at 4 weeks post-DMM. The insert shows an expanded view of the highlighted black box. c Histological scores of the safranin-stained sections. Values are mean ± SEM (n = 7). LFC = lateral femoral condyle; LTP = lateral tibial plateau; MFC = medial femoral condyle; MTP = medial tibial plateau. Scale bar = 100 μm