Fig. 11. Methylprednisolone acetate 80 mg/ml, long-term sacrifice. (A ) Diffuse inflammatory infiltrates and fibrosis in arachnoid. Arrows  indicate regions shown at higher power in C  and D  (bar = 3 mm). (B ) Immunofluorescent staining for Iba1 (green ). The large cell in the center is an activated microglia. There are multiple smaller resting microglia in the surrounding tissue. (C ) Fibrosis and macrophage infiltration in arachnoid and inflammatory cell infiltration of a nerve root (bar = 100 μm). (D ) Focal aggregate of pigment-laden macrophages in arachnoid (bar = 100 μm). (E ) Large arachnoidal inflammatory mass. Arrows  indicate regions shown at higher power in F –H  (bar = 3 mm). (F ) Mixed inflammatory infiltrate away from inflammatory mass. (G ) Granuloma formation with epithelioid macrophages within inflammatory mass. (H ) Perivascular inflammation and vasculitis. B –D , bar = 100 μm.