Lymphatic tissues refer to the tissues of the body that form part of the lymphatic system. The lymphatic tissues of the body generally include the spleen, thymus, adenoids, tonsils, and bone marrow, as well as the lymph nodes. These organs are responsible for producing lymph, the generally transparent fluid that circulates through the body's interstitial spaces. Lymph is composed mostly of the T-cells, antibodies, and macrophages that provide the body's immunity. Some physicians consider the lymph fluid to be a lymphatic tissue as well.
The human immune system is believed to rely entirely on the proper functioning of lymphatic tissues. The organs and fluids of the lymphatic system are responsible for removing pathogens from the body's organs and blood stream. The lymph nodes may be the most commonly recognized lymphatic tissues. They are usually located in the groin, underarms, and chest regions, and they're usually small and oval shaped. They are responsible for filtering the lymph, eliminating pathogens found in the lymph, and producing the antibodies that protect against disease.
The lymph itself, also considered by some to be a lymphatic tissue, is generally identified as a transparent fluid that circulates through the body's interstitial spaces, or the spaces between organs. It usually contains white blood cells and antibodies.
The thymus, an organ typically found in the upper torso, between the left and right lung, also usually forms part of the body's lymphatic tissues. Immature T-cells generally find their way to the thymus, where they are able to continue maturing. Pathogens generally cannot penetrate the epithelial-reticular cells that protect the thymus. It can therefore provide a safe environment for the production of mature T-cells.
The spleen may be one of the body's most important lymphatic tissues, for the many physical functions it serves. The spleen, which can usually be found behind the stomach and in front of the diaphragm, contains both red and white pulp. Both types of pulp contain connective tissues, lymphocytes, and macrophages.
Together, the spleen's red and white pulp are responsible for filtering the blood to remove pathogens and red blood cells that are no longer functional. The red pulp is considered capable of storing significant amounts of extra blood, which can be released into circulation as necessary. The spleen can also produce new red and white blood cells, as can the bone marrow. Lymphocytes and macrophages usually congregate in the white pulp, where they can be dispatched if an immune response occurs in the body.