Figure 4From: Intra-articular injection of collagenase in the knee of rats as an alternative model to study nociception associated with osteoarthritisProgression of histopathological changes in knee joint sections stained with Fast Green and Safranin O. A: Control animals show unaltered articular cartilage (AC) and subchondral bone (SB). Animals injected with 250 U collagenase (B, C, D, E) show increased thinning of the articular cartilage throughout time, along with focal chondrocyte disorganization. Animals injected with 500 U (F, G, H, I) show signs of OA onset at week 4 ( H ) that further develop until week 6 ( I ) when extensive damage of the articular cartilage is observed. Bar: 50 μm.Back to article page