what organs is the lymphatic system made up of
The components of the lymphatic system are divided into two groups â the primary organs and the secondary organs. 1  Primary Organs: The thymus gland and the bone marrow are primary organs. They regulate the production and differentiation of lymphocytes â the cells that make up the immune system. Secondary Organs: The secondary organs include the lymphatic vessels, lymph nodes, aggregated lymphoid tissue, and spleen. These secondary organs are involved, to some extent, in all three lymphatic functions.