Lymphatic tissue: A part of the body's immune system that helps protect it from bacteria and other foreign entities. Lymphatic tissue is rich in lymphocytes (and accessory cells such as macrophages and reticular cells).The lymphatic system is a network of tissues and organs that help rid the body of toxins, waste and other unwanted materials. The bone marrow and thymus are primary lymphoid tissues and the sites of lymphocLocated in almost every tissue in the body, these vessels are interlaced among the arterioles and venules of the circulatory system in the soft connective tissues yte development. The lymph nodes, spleen, tonsils and Peyer's patches. The tissues and organs that produce, store, and carry white blood cells that fight infections and other diseases. Secondary lymphoid tissues are sites where lymphocytes interact with each other and nonlymphoid cells to generate immune responses to antigens. Scattered cells and lymphoid tissue, as well as slightly more organized lymph nodules, are commonly found in the mucosa of the GI tract.