Histological analyses of limb joints. The 4 limbs were excised from all mice at 14 days after injection of a cocktail of antibodies to type II collagen. Decalcified 8-μm sections of hands (A-D), elbows (E-F), toes (I-L), and knees (M-P) from RA-/Ab- (A, E, I, M), RA-/Ab+ (B, F, J, N), RA+/Ab- (C, G, K, O), and RA+/Ab+ (D, H, L, P) mice were stained with hematoxylin and eosin. Synovial thickening and accumulation of inflammatory cells were observed in joints from the RA+ mice (arrowheads in panels C, D, G, H, K, L. O, and P). Bars: 500 μm (A-D, I-P ) and 200 μm (E-H).