A, B. Left foreleg of a mouse 24 h post onset of clinical signs (score 3). R - radial bone; arrowhead: accumulation of degenerate neutrophils, arrow: epidermis. C-F. Left foreleg of a mouse 5 days post onset of clinical signs (score 4). R - radius, * - joint space. E. Neutrophils in the infiltrate are found to express NETs (arrowheads). F. Macrophages can be seen in moderate numbers (arrows). A, C: HE stain; B, D-F: HRP (Iba-1, histone H3) and ABC (Ly6G) method, hemalaun counterstain. Bars = 200 μm (A), 100 μm (B, D-F). 2.5 mm (C).