Fig. 5. Aβ^pH is phagocytosed by microglia and astrocytes in vivo in the cerebral cortex. (A) Schematic of how Aβ^pH phagocytic uptake is imaged through a cranial window in vivo in real time using two-photon excitation microscopy. (B) In vivo two-photon imaging of the mouse barrel cortex before and after topical application of Aβ^pH. The fluorescence increases in cell somata (indicated by red circles) reflecting Aβ^pH uptake. Shadows in the right image are created by the presence of pial and intraparenchymal vessels. (C) Quantification of mean Aβ^pH fluorescence in cell somata over time. The data were normalized to the maximum mean Aβ^pH fluorescence for each cell and then averaged. Data shown as mean ± s.e.m. N = 59 somata from 2 animals. (D) 1.5 to 3 hours after in vivo two-photon imaging of Aβ^pH, animals were perfusion-fixed and cortical slices were stained for microglia, lysosomes/endosomes, and astrocytes using IBA1, CD68, and GFAP antibodies, respectively. (E) Quantification of Aβ^pH colocalization with IBA1, CD68, and GFAP suggests that most Aβ^pH is taken up by microglia and astrocytes in vivo. Data shown as mean ± s.e.m. N = 12 stacks from 3 animals.