Figure 2.

Tau pathology in AD: Neurofibrillary tangles (NFTs) (A,B) and neuritic plaques (C,D). Flame-shaped intracellular NFTs (arrow) can be detected as bundles of basophilic filaments in pyramidal neurons of the hippocampus (A). Immunohistochemistry for phospho-tau shows not only NFTs (white arrow), but also pervasive neuropil threads and a pretangle (black arrow) that are not visible with routine histology. Neuritic plaques (asterisk) can also be detected with routine histology (C) because of central dense amyloid, clusters of swollen cell processes, activated microglia, and surrounding reactive astrocytes (arrow). Immunohistochemistry for phospho-tau shows clusters of irregular, swollen cell processes around a central unstained region (D) (i.e., amyloid core [asterisk]). Note also neuropil threads and several NFTs and pretangles (arrows). (Immunohistochemistry with CP13, whose epitope is near phosphoserine 202.)