Fig. 10. Methylprednisolone acetate 80 mg/ml, acute sacrifice. (A ) Focal subdural aggregates of macrophages surrounding foreign material (bar = 3 mm). Arrows indicate regions shown at higher power in B and C . (B ) Subdural aggregates of macrophages surrounding foreign material (bar = 200 μm). (C ) Mild arachnoid inflammatory infiltrates (bar = 100 μm). (D ) Higher power of region shown in B (bar = 100 μm). (E ) Caudal sacral section demonstrating severe inflammation in dura and arachnoid, with large inflammatory mass (bar = 300 μm). Arrow indicates region shown at higher power in F . (F ) Higher power of inflammatory mass, with inflammation in dura and arachnoid; necrotic center with neutrophils resembling an abscess (bar = 100 μm).