Frozen section of a mouse lymph node, stained with a fluorescent antibody specific for T-cells. The cells within the diffuse cortex (DC) are uniformly stained, whereas only few stained cells are visible in the primary follicle (PF).
At the right a high endothelial venule (HEV) is visible, the site of entry of lymphocytes from the blood into the node. Several T-cells are visible within its lumen.