(C) 3D reconstruction of the old APPPS1/CX3CR1+/GFP slice in co-culture with the young WT slice (10 DIV) and immunostained using GFP (green) and M3.2 (red). GFP positive old microglial cells surrounding amyloid plaques exhibit intracellular M3.2 positive immunoreactivity indicative of Aβ uptake. Overview at low magnification is shown in the left panel. Scale bar: 15 µm. A detailed plaque is shown at higher magnification in the right panels. Scale bar: 10 µm. 