Fig. 2

Histological examination of knee sections from SCID mice. a Sections from healthy untreated knee joint (Fem femur, Tib Tibia). Arrows indicate a normal synovial membrane. b Knee joints 100 days after transfer of FLSs isolated from C57BL/6 mice with acute AIA. Shown is an overview of the inflamed and destructed joint (Fem femur, Tib tibia). Arrows indicate the hyperplastic and inflamed synovial membrane. Asterisks indicate the inflammatory exudate in the knee cavity. c and d Higher magnification to illustrate hyperplasia of the synovial lining layer and pannus formation (arrows) and inflammatory infiltration (asterisks) and neovascularization (thick arrows). e and f Cartilage erosions (arrows) and necrosis of chondrocytes (asterisks). Staining of proteoglycans with Safranin O in healthy knee joint sections (g, i) and arthritic knee joint of SCID mice (h, j) 100 days after cell transfer shows loss of proteoglycans in arthritic SCID joints. Sections a–f were stained with H&E, g–j with Safranin O. Magnifications: a, b, g, h 40×, i, j 100×, c, d, f 200×, e 400×