Figure 2a. (a) Transverse thin-section CT scan of the left lower lobe of a pig subjected to hyperoxia for 72 hours shows a mosaic pattern of lung attenuation that consists of spared areas (arrowheads) and areas of ground-glass opacity with thickened interlobular septa (arrows). The spared areas correspond to the early exudative histologic phase of DAD. (b) Stereomicroscopic view of an area of the right lung that corresponds to the area of ground-glass opacity in the left lung in a. Note that the secondary pulmonary lobule is diffusely involved with thickened interlobular septa (arrows). (c) Histologic specimen that corresponds to the boundary between the spared areas (right) and the areas of ground-glass opacity (left) in a shows a thickened interlobular septum due to edema (arrow) that demarcates the involved from the less involved lobules. (Hematoxylin-eosin stain; original magnification, x5.) (d) Histologic specimen that corresponds to the areas of ground-glass opacity in a shows intraalveolar fibrinous exudates and hyaline membranes (arrows), which are features of the exudative phase of DAD. (Hematoxylin-eosin stain; original magnification, x100.)