Histology of affected joints of animals with early-onset arthritis induced with chicken-origin collagen type II. Histology of the affected joint of a representative animal with early-onset arthritis (M03136) induced with chicken-origin collagen type II. (a) The swollen joint, subsequently analyzed for histopathology in panels (b) to (e). (b) Overview of the affected joint. (c) Focus on the phenomena observed in (b) displaying prominent extraarticular infiltrates and highly active bone marrow, (d) resulting in erosion of the bone and disruption of the cartilage. (e) Manifestation of subcutaneous inflammation and infiltrates at the periosteum.