Histopathology of tarsal joints from day 8 and until decline of symptoms. (A) Appearance of cartilage (encircled) marks the onset of endochondral ossification (day 8). (B) Ankylosis has progressed from being fibrous to consist of cartilage and osteoid (day 10), with osteoid closest to the original bone (arrow). (C) Declining disease phase: bone formation is remodelled with OC activity observed in some animals (arrow). (D) Histological scores of bone erosion (black bars) and bone formation (grey bars) over time (mean +/− standard deviation (SD)). Statistics from the comparisons of individual groups is indicated by lines above the bars (Dunn’s multiple comparison test, *P <0.05, **P <0.01, ***P <0.001). OC, osteoclast.