Aβ deposition in the subiculum is associated with high levels of microglial reactivity. Double immunofluorescence staining of 6-month-old EFAD subicula revealed significant Aβ deposition and elevated microglial activation in each group. (A) Representative images of fluorescence staining in EFAD subiculum. Aβ-associated microglial activation was assessed for each APOE genotype (n = 4 or 5 mice/APOE genotype). Scale bar: 30 μm. (B) Microglial density, fluorescence intensity and percentage area of the plaque domain did not differ between APOE genotypes. Within the subiculum, the reactive microglia in each group occupies a large percentage of the plaque domains relative to the deep cortex.