CD68 and Alzheimer disease: To understand the spatio-temporal and functional differences between plaque-phagocytic and non-phagocytic microglia in AD, we took advantage of in vivo Aβ plaque labelling using a fluorescent Congo-red derivative, methoxy-XO425, which co-localized with CD68+ phagosomes in plaque-associated Iba1+ microglia (Fig. 1a, b and Supplementary Fig. 1a–c).