Representative micrographs of MWCNT in subpleural tissues, visceral pleura and pleural space. In all four panels, the visceral pleural surface runs along the top of each micrograph. The FESEM image in A shows a MWCNT loaded alveolar macrophage in an alveolus immediately beneath the visceral pleura surface. The right side of the image shows a single MWCNT fiber penetrating the alveolar epithelium into the subpleural tissues (80 μg dose, 28 day post-aspiration). Figure 7B shows a dilated subpleural lymphatic vessel which contains a mononuclear inflammatory cell that is penetrated by several MWCNT fibers (80 μg dose, 56 day post-aspiration). A MWCNT penetrating the visceral pleura is shown in the light micrograph of 7C with a MWCNT-loaded alveolar macrophage visible in the left side of the micrograph (80 μg dose, 28 day post-aspiration). A single MWCNT penetrating from the subpleural tissue through the visceral pleura into the pleural space is shown in the FESEM image of 7 D (80 μg dose, 56 day post-aspiration).