Overview of moderate inflammation (A+D), severe inflammation (B+E), complete destruction (C+F) and syndesmophyte formation (G). Panel A, B, C and D are H&E stainings; panel E, F and G are toluidine blue stainings. All panels are at 100x magnification, except panel D at 500x, which is a magnification of the rectangle in panel A, and panel G at 25x magnification. Arrows point towards foci of hypertrophic chondrocytes and new formation or syndesmophytes (panel G), which are typically located outside the joint. 1-cartilage endplate, 2-bone with bone marrow, 3-annulus fibrosus, 5-connective tissue.