Figure 3.

Lymphocyte delivery to PLN of L-selectin–deficient mice does not lead to platelet accumulation in HEV. The micrographs show a segment of the same HEV as in Fig. 2 (blood flow from right to left) 10 min after injection of activated human platelets. (A) A rolling aggregate of bright 2′7′-bis-(2-carboxyethyl)-5(and 6) carboxyfluorescein– labeled platelets with a fainter rhodamine 6G labeled WBC in their midst can be seen (arrow). (B) 2 s later, the platelet–WBC aggregate has arrested firmly. Labeled platelets are initially distributed randomly on the surface of the stuck cell. (C) Within 5 s after the WBC had become stuck, platelets roll slowly downstream across the body of the adherent cell and eventually detach. (D) 30 s later, all platelets have detached and returned to the blood stream, whereas the WBC remains stuck at the HEV surface.