Morphometric changes (A) and Sirius red-stained lung sections (B-E) from C57BL/6 mice 28 days following exposure to CNF, Crocidolite Asbestos or SWCNT. A: Collagen fiber content determined as average thickness of connective tissue; Inset: Granulomatous cellular tissue; B: Control; C: CNF; D: Asbestos; E: SWCNT (Arrow indicate collagen accumulation). Mice were exposed via pharyngeal aspiration to 120 μg/mouse CNF or Asbestos, or 40 μg/mouse SWCNT. Animals were sacrificed 28 days post exposure. Means ± SE (n = 6 mice per group). *p < 0.05 vs. control (PBS) exposed mice, αp < 0.05 vs. mice exposed to CNF, βp < 0.05 vs. mice exposed to asbestos.