postcapillary venule high endothelial venule BTO:0004528 HEV NCIT:C32739 High endothelial venules are specialized blood vessels adapted for lymphocyte trafficking. They form a spatially organized network, which controls both the type of lymphocyte and the site of entry into lymphoid tissues. Uniquely, high endothelial venules express vascular addressins that regulate lymphocyte entry into lymphoid organs. They perform this function in all lymphoid organs except the spleen. UBERON:8410037