Rolling neutrophils form ENDS. (A–E) Mouse neutrophils were labeled with Ly6G-AF647. Blood flow was from left to right. (A) Consecutive frames show ENDS (arrows) sliding along the venular wall and then detaching. Scale bar, 8 µm. (B) Examples of mouse ENDS with bead-like structures in vivo. Scale bars, 6 µm. (C) Consecutive frames show ENDS flowing in arteriolar blood stream. Scale bar, 8 µm. (D) ENDS detected with confocal microscopy in isolated blood plasma. Blood was collected at the end of the imaging session via a femoral artery cannula. Scale bar, 8 µm. (E) After rolling of unlabeled neutrophils, the flow chamber was stained with CD16-AF647 antibody and was scanned with bright-field and fluorescent imaging. The upper panel shows the record of the entire chamber; on the upper bright-field panel, the rectangles are imaging artifact; the lower panel shows the CD16-AF647 signal to the left behind ENDS. Rectangles indicate the magnified areas. Scale bars represent 1 mm (top image) and 0.5 mm (bottom images). The spherical objects within the magnified areas (indicated by arrows) are neutrophils that remained in the flow chamber after washing. (F) Length of human ENDS formed during rolling on E-selectin under a WSS ramp.