Plaque morphology in MS cases. Paraffin wax sections stained with LFB (A1, B1 and C1) and anti-HLA DR (A2, B2 and C2) showing an active (A1-A2; case MS160_S3), chronic active (B1-B2; case MS225_S13) and chronic inactive plaque (C1-C2; case MS61_B). The active plaque shows profound inflammation with anti-HLA-DR immunopositive microglia (A2 and inset) and foamy macrophages containing myelin degradation products demonstrated using LFB (inset in A1). The chronic active plaque shows little inflammation in the centre of the plaque (insets in B1 and B2) but abundant anti-HLA-DR immunopositive microglial at the plaque border (B2). The chronic inactive plaque shows an immunologically silent lesion centre (inset in C1 and C2) and a well demarcated lesion border showing only mild inflammation (C2 and inset) Scale bars are shown in B2 and are applicable for all plates and inserts.