II. LYMPH NODES
The lymph nodes are the only lymphatic organs which are interposed in the course of lymphatic vessels and thus possess both afferent and efferent connections. Grossly, the lymph node has a bean or kidney shaped form which may be slightly indented in one side.
Lymph Node (H&E) [#37]: Study the arrangement of the stroma which consists of the capsule and trabeculae of connective tissue (mainly collagen), and the reticular connective tissue stroma (which cannot be distinguished in H&E preparations). Note that the lymph node has a peripheral zone (cortex) which is divided by thin connective tissue trabeculae into compartments that contain lymph follicles surrounded by lymph sinuses. Locate the subcapsular lymph sinus (arrow). The central part of the lymph node is the medulla. It contains irregularly-arranged trabeculae enclosing the medullary lymph cords and sinuses. Locate the hilum of the lymph node and find the efferent lymphatic vessel. Locate an afferent vessel on the convex surface of the node.