Figure 5. Photomicrographs of liver, spleen, and lung sections from influenza virus A (H5N1)–infected mice at endpoint. Necrotic foci (arrows) scattered throughout the liver (A) (original magnification ×200) and spleen (B) (original magnification ×100) from subtype H5N1–infected mice (hematoxylin and eosin stain); these foci are absent from subtype H1N1–infected mouse livers. C) Necrotic foci in the liver stain periodic acid–Schiff (PAS)–positive (arrow), which suggests focal accumulation of glycogen (original magnification ×400). D) Numerous alveolar walls lined with PAS-stained hyaline membranes (arrows), suggestive of necrosis and desquamation of pneumocytes (original magnification ×1,000).