Ramified and dystrophic microglia are associated with amyloid-beta protein deposits. Double-label immunohistochemistry for Aβ protein (brown reaction product; 4G8 antibody) and microglia (black reaction product; Iba1 antibody) in human cerebral cortex. A, diffuse Aβ deposits are colocalized with ramified, non-activated microglia, B, as Aβ deposits become more compact microglia begin to show signs of dystrophy (arrow points to early fragmentation and spheroid formation). C, D show several advanced dense-core plaques where the dense core is comprised of dystrophic microglial fragments (white arrows). Note multiple microglial fragments in the immediate vicinty of Aβ deposits. Bar = 50 μm.