Microgliosis is observed near degenerating apical dendrites of Betz cells in motor cortex of ALS patients. Representative images of apical dendrites (Map2+) located in layer IV of the motor cortex isolated from normal controls and ALS patients. a, d Apical dendrites appear healthy in normal controls, and there is no evidence of gliosis. Insets are enlarged at the bottom. b–f Vacuolated apical dendrites with obvious structural defects are present in both sALS (b, e) and fALS (c, f) cases with microgliosis (Iba1+) and astrogliosis (GFAP+). In some cases, activated microglia are in contact with degenerating apical dendrites (c, arrow and e, f), and abnormal rod-like microglia are also observed (f). Insets are enlarged at the bottom. Number sign marks normal microglia; arrows point to activated microglia. Abbreviations: sALS sporadic ALS, fALS familial ALS. Scale bar = 20 μm (a–c), scale bar = 10 μm (d–f).