Figure 3

A,B,C; Lung histology of uninfected mice exposed to; A) intranasal PBS and B) 2× doses of 500 μg ultrafine-carbon black (UF-CB). Sections were imaged under light microscopy (200×). Figure C) shows lung tissue of an UF-CB exposed animal under higher power (400×). Changes induced by UF-CB are given in Table 1. The most distinctive feature is carbon-laden alveolar macrophages (arrow). There is no evidence of free carbon in the airway, or significant uptake of carbon by other airway cells.