FIG. 2.

Histological sections of the nasal cavities of control BALB/c mice (A) and BALB/c and CFTR^−/− mice 24 h after inoculation of strain COL (B and C, respectively). Hematoxylin-eosin (upper panel, 25× enlargement; middle panel, 400× enlargement of selected area) and Gram staining (lower panel, 1,000×) were performed with 5-μm-thick sections. Luminal cellular clumps spread along the nasal cornets are indicated with arrowheads (B₁ and C₁) and asterisks (B₂ and C₂). Bacteria that appeared to be located intracellularly within the cellular clumps composed of neutrophils and degenerated cells are denoted with an arrow (B₃ and C₃). In CFTR^−/− mice, bacteria were present along the nasal epithelium (C₃).