Slide A
In this low power view, the airspaces appear irregular in shape, with thickened walls. This apparent thickening is caused by alveolar septa collapsed against one another; the residual airspaces are mostly alveolar ducts and some proximal alveoli, while most of the peripheral alveoli are unexpanded.

Slide B
This view shows a respiratory bronchiole opening into an alveolar duct that is lined by a hyaline membrane. The apparent cellularity of the adjacent alveolar parenchyma is caused by the marked atelectasis and immaturity of the lung tissue.