(A) Immunofluorescence analysis of the old APPPS1 slice in co-culture with the young CX3CR1+/GFP slice (14 DIV) and immunostained using GFP (green), CD68 (red) and M3.2 (blue) reveals no co-localization of young, GFP positive microglial cells with CD68 positive cells surrounding amyloid plaques. A GFP antibody was used to amplify the signal of GFP-expressing young microglial cells.(B) Immunofluorescence analysis of the old APPPS1/CX3CR1+/GFP slice in co-culture with the young WT slice (14 DIV) and immunostained using GFP (green), CD68 (red) and M3.2 (blue) reveals co-localization of old, GFP positive microglial cells with CD68 positive cells surrounding amyloid plaques. A GFP antibody was used to amplify the signal of GFP-expressing old microglial cells. Scale bar: 10 µm (A and B). 