<P> Lymph nodes also have clinical significance . They become inflamed or enlarged in various diseases which may range from trivial throat infections, to life - threatening cancers . The condition of the lymph nodes is very important in cancer staging, which decides the treatment to be used, and determines the prognosis . When swollen, inflamed or enlarged, lymph nodes can be hard, firm or tender . </P> <P> Lymph nodes are kidney or oval shaped and range in size from a few millimeters to about 1--2 cm long . Each lymph node is surrounded by a fibrous capsule, which extends inside the lymph node to form trabeculae . The substance of the lymph node is divided into the outer cortex and the inner medulla . The cortex is continuous around the medulla except where the medulla comes into direct contact with the hilum . </P> <P> 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 . 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 . </P> <P> The number and composition of follicles can change especially when challenged by an antigen, when they develop a germinal center . Elsewhere in the node, there are only occasional leucocytes . As part of the reticular network there are follicular dendritic cells in the B cell follicle and fibroblastic reticular cells in the T cell cortex . The reticular network not only provides the structural support, but also the surface for adhesion of the dendritic cells, macrophages and lymphocytes . It allows exchange of material with blood through the high endothelial venules and provides the growth and regulatory factors necessary for activation and maturation of immune cells . </P>

Where are t lymphocytes located in lymph nodes