Fig. 8

Histopathological examination of lung and tracheal tissues from mice inoculated with H4N1 AIVs. (a) HE-stained lung sections at 3 dpi with CS01, showing slight hemorrhage (a1), epithelial cell shedding (a2), and lymphocyte aggregation (a3). (b) Lung sections from mice inoculated with CS01-A4 at 3 dpi, revealing bronchial epithelial cell shedding (b1), pulmonary hemorrhage (b2), and lymphocyte aggregation (b3). (c) Lung sections from mice inoculated with CS01-A7 at 3 dpi, demonstrating lung consolidation, extensive lymphocyte infiltration around the trachea (c1), necrosis and shedding of bronchial epithelial cells (c2), inflammatory cell infiltrates in alveolar cavities, and intra-alveolar hemorrhage (c3). (d-f) HE-stained tracheal sections at 3 dpi with CS01, CS01-A4, and CS01-A7, respectively, showing ciliary necrosis and shedding in (d) and (e), and more severe changes including necrosis, shedding of epithelial tissue, tracheal wall thickening, and lymphocyte infiltration in (f). (g) HE-stained tracheal section from the control group, showing normal tissue structure. Images were acquired using a digital slide scanning system (Zeiss). In the inserts surrounding figures a, b, and c, the images were magnified tenfold