PTPRC and Alzheimer disease: Quantitative analysis of the hippocampal area occupied by the CD45‐positive immunostain revealed that 3xTg‐AD mice injected with the old‐Tg mice brain homogenate had significantly less CD45‐microglia in the hippocampal region in both the ipsilateral (78% ± 5.00% reduction) and contralateral (75% ± 10.90% reduction) sides in comparison with 3xTg‐AD mice treated with the human brain extract (one‐way ANOVA, F(4, 25) = 5.766, p = 0.0020, Tukey's multiple comparisons tests, Figure 3F).