Figure 9.

Electron micrographs of lung samples 0 (A), 1 (B and C) 7 (D), and 9 hours (E and F) after BV13 infusion. In A, normal vascular endothelial cell morphology is present. In B, some neutrophils are evident (open arrows) in lung capillaries. C shows platelet (P) aggregates present in venules. In D, endothelial cells present blebbing (black arrows). In E and F, multiple gaps and breaks are evident (black arrows), and platelets aggregates are present (P). Neutrophils (open arrows) appear to be adhering to denuded basement membrane and passing through the gaps in vascular wall (E). Interstitial cell debris are present in the vascular lumen (F, double-headed arrow), where the endothelial cell barrier has been lost. Sections were stained with uranyl acetate and lead citrate. (×4,800.)