Figure 4.

CM is associated with impaired perfusion in pial vessels. A–D: Four consecutive sections of the same venule showing how adherent leukocytes can cause marked reduction in luminal diameters and impair perfusion (a more detailed dynamic view is available at the supplemental video S3, at http://ajp.amjpathol.org). Asterisks show adherent leukocytes. The luminal diameter in specific sections is shown (black bars with the respective diameter value); note the large variations in diameter mostly attributable to adherent leukocytes, and a site of major constriction in B with apparent damage of the vessel structure. Bright spots in A and D are flowing fluorescent PbA-GFP pRBCs. Adherent leukocytes can completely block blood flow in small venules. E and F: Two consecutive frames showing vessels stained with albumin-FITC, one of them is nonperfused (arrow) blocked by an adherent leukocyte (asterisk; E) and the same area showing the leukocyte stained with anti-CD45-TxR antibodies (F; see dynamic view in supplemental video S5, at http://ajp.amjpathol.org). G and H: Collapse of nonperfused small vessels: disappearance of small vessels with no flow (white arrows), and associated nonflowing vessels (black arrows).