Evolution of histologic changes in the presence of macrophage-depleting agent clodronate following LC injury. The right lungs at the area of grossly identified contusion were fixed and processed for hematoxylin and eosin staining. Clodronate groups showed increase inflammatory attributes (hemorrhage, cellular infiltrates, alveolar edema) in comparison with respective controls at early time points (5, 24, and 48 hours). At 72 hours, both groups (liposome and clodronate) seem to have similar recovery from LC injury. See text for details. Bar, 50 μm.