Fig. 3

Scoring of the severity of microglial dystrophy and examples of rod-shaped and hypertrophic microglia. Iba1 immunohistochemical staining showing representative images of the semi-quantitative analysis of microglial dystrophy and the different microglial morphologies. Grey matter sections from a healthy control (a, case 2 in Supplementary Table 1) and four different FTLD cases (in Supplementary Table 1: b case 44; c case 22; d case 42; e case 37) show appearances of dystrophic microglia, graded in severity, from a (1 = no dystrophy), b (2 = mild dystrophy), c (3 = moderate), d (4 = severe), to e (5 = very severe). When dystrophy is very severe, minimal staining is visible due to complete disruption of normal cell structure. f Several rod-shaped microglia in the frontal grey matter of an FTLD-TDPB case with the C9orf72 expansion (case 48; black arrows point to these cells). g Multiple hypertrophic microglia throughout the frontal grey matter of an FTLD-Picks case (case 25; most cells present have a bushy appearance with short, thick processes). Scale bar represents 50 μm in all images