Fig. 5

Lung tumors found in MWNT-7-treated rats. A Bronchiolo-alveolar adenoma in a rat of the high-dose group. Underlying alveolar architecture is obscure, and MWCNT-deposited areas appear to be compressed to the peripheral regions. B Bronchiolo-alveolar adenocarcinoma in a rat of the high-dose group. Tumor shows nodular growth (approximately 5 mm in diameter) and invasion of the surrounding tissues. C Higher magnification of (B). The tumor exhibits a glandular growth pattern with structural atypia. D Bronchiolo-alveolar adenocarcinoma in a rat of the low-dose group. Inset: immunostaining for TTF-1. The tumor shows aggressive invasion toward the visceral pleura at the right-posterior lobe, a primary site. E Translocated cells found on the surface of the right-anterior lobe. Inset: immunostaining for TTF-1. F Nonkeratinizing epithelioma (synonymous with benign nonkeratinizing squamous cell tumor) in a rat of the high-dose group. The alveolar space is filled with squamous cells with round to oval nuclei and fine granular eosinophilic cytoplasm