Light micrograph of MWCNT deposition in alveolar region of lungs. Sirius Red stained micrograph showing the general deposition pattern of MWCNT (arrows) one day after aspiration. A deposit of MWCNT on the epithelium of the terminal bronchiole (TB) near the transition between the airways and the alveolar region is indicated by the asterisk. Smaller deposits near the subpleural tissue region are indicated by double arrows. (dose 80 μg).