Intracellular Aβ appears at 3 months and is enhanced by 6 months in 3xTg-AD mice. Coronal brain sections from 2, 3 and 6 month-old 3xTg-AD and non-transgenic mice were stained with human APP/Aβ-specific 6E10 antibody and developed using DAB. Panel A illustrates that the brains of 2 month-old 3xTg-AD mice are pre-pathologic, while at 3 months, hAPP/Aβ can be readily detected in both the entorhinal cortex and hippocampus of 3xTg-AD mice. By 6 months of age, 3xTg-AD mice exhibit further enhanced deposition of hAβ in both regions. Panel B identifies sections of entorhinal cortex and hippocampus from non-transgenic mice, which are not immunohistochemically positive for endogenous mouse Aβ, therefore indicating that the 6E10 antibody specifically detects transgene-driven expression of hAPP/Aβ in 3xTg-AD mice. The scale bars depict 50 μm. The insets represent 60× magnification.