where does the lymphatic system begin and end
Lymphatic system The lymphatic system is part of the circulatory system and an important part of the immune system, comprising a network of lymphatic vessels that carry a clear fluid called lymph (from Latin, lympha meaning "water"[1]) directionally towards the heart. The lymphatic system was first described in the seventeenth century independently by Olaus Rudbeck and Thomas Bartholin. Unlike the circulatory system, the lymphatic system is not a closed system. The human circulatory system processes an average of 20 liters of blood per day through capillary filtration, which removes plasma while leaving the blood cells. Roughly 17 litres of the filtered plasma are reabsorbed directly into the blood vessels, while the remaining three litres remain in the interstitial fluid. One of the main functions of the lymph system is to provide an accessory return route to the blood for the surplus three litres.[2]
Lymph node Thin reticular fibers of reticular connective tissue, and elastin form a supporting meshwork called a reticulin inside the node. B cells are mainly found in the outer (superficial cortex) where they are clustered together as follicular B cells in lymphoid follicles and the T cells are mainly in the paracortex.[6] The lymph node is divided into compartments called lymph nodules (or lobules) each consisting of a cortical region of combined follicle B cells, a paracortical region of T cells, and a basal part of the nodule in the medulla.[7]