Fig. 3

Representative images of collateral ligaments in OA Str/ort mouse knee joints. a Toluidine blue, collagen type II (Col2) and Sox9 immunolabelling in healthy CBA mouse collateral ligaments, with high magnification of the body of the ligament. b Collateral ligaments from Str/ort mouse knee joints with OA grades of 5 (severe). Toluidine blue staining showed increased staining with hypertrophy of local cells. Col2 deposition and sox9-positive cells were also increased. c Very severe OA joints showed severe changes including ossification within the body of the ligament (red arrows) and areas of col2 deposition and Sox9-expressing cells (black arrows). Low mag = low magnification, scale bar = 100 μm; High mag = high magnification, scale bar = 50 μm. For orientation: femur at top of picture, tibia bottom