Development of Aβ plaque pathology in the hippocampus of APP/PS1 mice. No Aβ-positive (green) plaques are observed in the hippocampus of APP/PS1 mice at 3 months of age, whereas at 6 months, all mice had few hippocampal plaques (arrows). Plaque load is further increased at 12 months. Parallel to the increase in plaque formation, there was a moderate increase in GFAP staining (red) around all plaques at 6 and 12 months of age. CA, cornus ammonis; DG, dentate gyrus. Scale bars: upper panels, 400 μm; lower panels, 100 μm.