Photomicrographs of tau (AT8, green) immunoreactivity in microglia (Iba1, red) in PFC of a 39-year-old male chimpanzee (subject 13): (a) microglial cell surrounded by a tau-ir (AT8, green) neuritic cluster with minimal tau localization intracellularly (white arrows, yellow), and (b,c) intracellular tau deposition in microglia (white arrows, yellow). Scale bars = 25 μm.