Fig. 2
Localization of chronic microinfarcts in different cortical layers with cell loss in the pigment Nissl (PN) stain and microvascular changes shown with collagen 4 (Coll4)-immunohistochemistry in two adjacent thick brain sections. a, c, e Microinfarcts are located at deep cortical layers, often extending to the juxtacortical white matter (a-b; superior frontal microinfarct, case 6), at superficial cortical layers (e-f; anterolateral superior frontal microinfarct, case 6) or transcortically (c-d; parietooccipital microinfarct, case 4). The core of the microinfarction zone (MI) exhibits pallor in the PN stain due loss of Darrow red-stained neurons (boundaries of the MI indicated by black arrow heads). The MI core further contains aldehyde fuchsine-stained microglial cells (inset a1; asterisk in inset e1; also see Braak et al., 2018) and, as a result of cell loss, extracellular lipofuscin granules (insets a2 and c1; open arrow head in inset e1) that are easily distinguishable from intracellular lipofuscin granules seen in surviving Darrow red-positive neurons outside the MI zone (open arrow in inset e2). b, d, f In the MI core, chronic microinfarcts display a dense Coll4-immunoreactive microvascular meshwork (b double-labeled for Campbell-Switzer, CS) with numerous string vessels (black arrows in insets b1 and d1). String vessels also decorate the zone surrounding the MI core (black arrows in f; black arrow in inset f1). Scale bars: 1000 μm (a-d) and 2000 μm (e-f)