Figure 11. Histopathologic changes in the bronchioles during time in ferrets inoculated with pH1N1.

On 0.5 dpi there was infiltration of neutrophils in the bronchiolar epithelium and lumen with mild peribronchiolar cuffing. On 1 dpi the number of neutrophils increased with necrosis of the epithelium, intraluminal cellular debris and peribronchiolar cuffing. On 2 dpi the necrosis was more severe than on 1 dpi. On 3 dpi there was denudation of the basement membrane and little regeneration of the bronchiolar epithelium with hyperplasia, peribronchiolar cuffing and occasionally cellular debris in the lumen. On 4 dpi there was increased epithelial hyperplasia with moderate cuffing. On 7 dpi the epithelium covered the basement membrane of the bronchiole with hypertrophic cells and moderate cuffing. On 14 dpi the epithelium was slightly hypertrophic with little cuffing. HE, 200×.