MAPT and Alzheimer disease: Interestingly, these Iba1-positive rod microglia that we solely observe in the HMW tau-injected PS19 mice are also present in the gray matter of the AD cases from where the tau seeds were extracted, showing that the injection model recapitulates the human AD pathological environment and suggesting that in the human AD brain rod microglia might be somehow triggered by oligomeric forms of tau.