Photomicrographs of corneal lesions in Plg^−/− mice. (a) Stromal vascularization (arrowheads) in regions underlying extended plaques; (b) Extensive cellular infiltration and anterior deposition of PAS⁺ material, yet relatively normal posterior stroma with only mild inflammatory infiltration; (c) corneal ulceration; (d) An extensive corneal plaque which contained (e) abundant fibrin(ogen) matrix; (f) Formation of a wedge-like projection of epithelial cells was identified underlying but not penetrating the shoulder region of a plaque. The acellular, eosinophilic material above the “wedge” appeared to bisect the epithelial layer, leaving a thin layer of necrotic squamous cells exposed. (g) A pupillary membrane (arrows) formed in mice with severe corneal lesions. (h) This aberrant membrane stained intensely for fibrin(ogen) (arrows) by immunohistochemistry (DM denotes Descemet's membrane). Panels a, c, d, f, and g are hematoxylin- and eosin-stained, panel b is PAS-stained, and panels e and h are fibrin(ogen) immunohistochemistry. Original magnifications are 100× (panels c and d), 200× (panels a, b, e, f, and g) and 400× (panel h).