Colocalization of clustered microglia and neurofibrillary tangles in transgenic rat brain. Neurofibrillary tangles (NFTs) were detected with the monoclonal antibody AT180, recognizing tau protein phosphorylated at Thr231 and Ser235 (A), respectively. Activated microglia were stained with the polyclonal antibody Iba1, specific for ionized calcium-binding adaptor molecule 1 (B). Confocal study showed that some NFTs colocalized with clusters of activated microglia (C). Scale bars: 100 μm.