This diagram is provided for orientation of the reader. This is an idealized diagram of the compartmentalization of lymph nodes. It shows the capsule of the lymph node (LN) in green with its afferent lymphatics (AFF; on top) and its efferent lymphatics (EFF) at the hilus. The subcapsular sinus (SS) and medullary (MS) sinuses are in yellow and the peripheral cortex in pink with its lymphoid nodules (follicles). Each nodule contains a germinal center which can be divided into a light (L) and a dark (D) region based on staining with H&E. Most of the FDCs are located in the light region. CLICK at the green arrow to see the morphology of FDCs. The paracortex (or deep cortical units; DCU) are adjacent to the peripheral cortex and are shown in blue. The paracortex contains T cells (dark blue) and interdigitating cells (IDC; white). Post capillary venules (PCV), also termed high endothelial venules (HEV), run through the paracortex. For the vascular supply to the lymphoid nodules see the red arteriole (A) entering the node at the hilus and the dark blue venule (V) leaving the hilus. The medullary cords (MC; in purple) extend from the lymphoid nodules into the medullary sinuses. MCs are shown to contain plasma cells (PC) which are known to enter from the germinal centers. In parts of the sinuses brown macrophages (MO) are shown. These are found in all MS. Reticular cells crisscrossing all sinuses are not shown.