Injections of brain extracts from AD and MCI patients increase fibrillar Aβ deposition in AD-transgenic animals. Hippocampal tissue from brain treated and untreated animals (n = 5-8) were stained with ThS and analysed with an epifluorescent microscope. The burden of ThS-positive deposits was compared among all different control and experimental groups. Representative pictures of the deposits in the hippocampus of all groups are shown (a). The scale bar corresponds to 250 μm. (b) Magnification of the regions (corpus callosum in AD and MCI, dentate gyrus in NDAN) labeled in rectangles in panel (a). Scale bar correspond to 100 μm. (c) The ThS stained area was measured and divided by the total brain area analyzed (ThS burden).