APP and Alzheimer disease: To test whether microglial morphology is altered due to Aβ accumulation, we analyzed two mouse models of AD that differ in the distribution of Aβ plaques in the brain; whereas Aβ accumulates more abundantly in the hippocampus in APPSw,Ind Tg mice (Mucke et al., 2000), the Aβ plaques are evenly distributed in the hippocampus and cortex in APP/PS1 Tg mice (Jankowsky et al., 2004) (Fig. S2, upper panels).