Fig. 3
Chondrocyte apoptosis associated with proteoglycan loss is delayed in DMM-operated ColIITgcog mice which exhibit increased levels of intracellular BiP protein prior to DMM. Apoptosis is delayed in mice homozygous for ColIITgcog (c/c) compared to wild-type (+/+) mice. a Representative knee joint medial compartment sections stained with safranin O (SO) to visualise the OA lesion at 2 weeks DMM and serial sections analysed by TUNEL (FITC) with DAPI counter-stain (blue). b Quantitation of TUNEL-positive cells shows a significant increase in apoptosis in the medial compartments of the 2-week DMM-operated joints compared to the lateral compartments in both +/+ and c/c mice (see a). Chondrocytes within the OA lesion in +/+ mice do not stain with DAPI, whereas chondrocytes in the OA lesion of c/c mice are labelled with TUNEL and DAPI (see arrows) indicating they are in the process of apoptosis and that they are delayed compared with +/+ mice. c Increased BiP protein (dark purple staining indicated by black arrows) in articular and growth plate chondrocytes of 9-week-old non-operated c/c compared to +/+ mice. The inserts are enlarged sections of the areas represented by the black boxes. Scale bar = 100 μm