Fig. 2From: Lowest observed adverse effect level of pulmonary pathological alterations due to nitrous acid exposure in guinea pigsEffect of HONO exposure on the respiratory tract observed under light microscopy using hematoxylin and eosin staining. a, b Main bronchus near the middle of right-lung middle lobe. c Alveolar duct regions. Arrows indicate smooth muscle cells in the interstitium of the alveolar duct regionsBack to article page