Figure 4.

H&E stains of aortic sinuses from typical L^−/−/A^−/− mouse at various ages. (a) 12 weeks of age. H&E staining reveals fatty deposits (red arrowheads) present in the small intimal compartment adjacent or attached to the base of the aortic valve. Original magnification, 200X. (b) 18 weeks of age. H&E stains display a diffuse thickening of the intimal compartment, consisting primarily of foam cells (red arrowheads) in addition to the appearance of focal acellular areas above the media (blue arrowheads). Original magnification, 200X. (c) 24 weeks of age. H&E stain demonstrating a well-formed fibrous cap (red arrowhead) encapsulating a foam cell laden core. Arterial wall distension (black arrowhead) is noted in the media associated with stretching of the elastic lamella. Original magnification, 100X. (d) 36 weeks of age. H&E stains indicate that, at this time point, an intermediate size lesion is evident. The cap consists of a thin layer of cells (red arrowhead) and focal acellular patches (blue arrowhead), cellular debris, extracellular lipids, and cholesterol clefts (black arrowhead) are observed within the core. Focal cellular aggregates within the core (yellow arrowhead) and arterial wall distention (green arrowhead) are evident. Original magnification, 100X. (e) 48 weeks of age. H&E stains show that at this later time point the thin cap consists of a monolayer to bilayer of cells with apparent breaks in the endothelium and sloughing of the cap (red arrowhead). Large acellular areas (blue arrowhead) are evident in the well-established lipid core and there are abundant cholesterol clefts (black arrowhead). The arterial wall appears stretched (yellow arrowhead). Original magnification, 100X. (f) 60 weeks of age. H&E staining shows that the complex lesion consists of a thin monolayer of cells in the cap region with intermittent acellular patches (red arrowhead). The acellular lipid core is expanded with calcium deposition and cholesterol clefts (blue arrowhead). Original magnification, 100X.