Fig. 1From: Pannus inflammation in sacroiliitis following immune pathological injury and radiological structural damage: a study of 193 patients with spondyloarthritisPathologic features of the cartilage in sacroiliitis (hematoxylin-eosin staining (a, c-f), safranin O-fast green staining (b)). a Subchondral pannus invasion into the cartilage, accompanied with chondrocyte hypertrophy degeneration (arrow with black outline). b Pannus invasion resulted in cartilage matrix depletion (arrow with orange outline). c Neovascular formation and fibrotic cartilage (arrow with yellow outline). d Granulation tissue repaired the destroyed cartilage (arrow with blue outline). e Synovium pannus that has invaded into the cartilage surface (arrow with green outline). f Endochondral ossification (arrow with red outline)Back to article page