Figure 4c. (a) Transverse thin-section CT scan of the left lower lobe of a pig subjected to hyperoxia for 120 hours shows diffuse dilatation of bronchioles (arrows) within areas of increased attenuation. (b) Stereomicroscopic view of the right lung that corresponds to the same level in the left lung in a shows diffuse bronchiolectasis (arrows) within secondary pulmonary lobules and septal thickening (arrowheads). (c) Histologic specimen that corresponds to the area of increased attenuation with traction bronchiolectasis in a shows type II pneumocyte hyperplasia and interstitial fibroblastic proliferation (arrow) associated with microatelectasis (arrowheads), which are features of the early proliferative phase of DAD. (Hematoxylin-eosin stain; original magnification, x40.)