Cerebral amyloid angiopathy: amyloid-beta (Aβ) in cortical and leptomeningeal artery walls. (a) Cortical artery with deposition of Aβ in its wall but with no Aβ in the glia limitans (pan-Aβ immunohistochemistry). Smear preparations of cortical arteries showing (b) a patchy transverse banding pattern of amyloid deposition with no amyloid deposits attached to the outer aspect of the artery and (c) transverse banding of amyloid associated with the basement membranes of smooth muscle cells [4, 5] (thioflavin S stain: confocal images). Pan-Aβ immunohistochemistry of cortical arteries showing (d) Aβ in the glia limitans but with no Aβ in the vessel wall, (e) deposits of Aβ in the artery wall and in the glia limitans but no continuity between the two Aβ deposits and (f) Aβ in an artery wall with a heavy deposit of Aβ in the glia limitans both surrounding the vessel and on the surface of the brain (top). There is no continuity between the staining in the vessel wall and the glia limitans. A cored amyloid plaque in the brain parenchyma is seen to the left of the artery. Leptomeningeal arteries showing (g) deposition of Aβ in the vessel walls (pan-Aβ immunohistochemistry) and (h) loss of alpha-smooth muscle actin staining in the artery walls in relation to the deposition of Aβ; arteries in (h) are the same as those in (g). (Immunohistochemistry for alpha-smooth muscle actin.) Scale bars = 20 μm (a-e, g, h) and 50 μm (f). Reprinted with permission from John Wiley & Sons, Inc. .