Primary lymphoid organs
The origin of lymphocytes occurs inside primary lymphoid organs. Those involve the thymus and the bone marrow.
- This is the site where lymphocytes are produced and mature.
- It is also the location where stem cells differentiate and mature into B and T cells
- Humans have two primary lymphatic organs – the thymus gland and the red bone marrow
- B and T cells are formed in the bone marrow
- B cells mature in the bone marrow while T cells mature once they migrate to the thymus.
Secondary lymphoid organs
Upon maturation, the lymphocytes move to a secondary lymphoid organ such as the spleen, lymph nodes, tonsils, small intestine and appendix patches of the payer. They include the sites for antigens to interact with lymphocytes.
- Secondary lymphoid organs serve as a sort of “monitoring station” for the contents of the extracellular fluids – such as the blood, lymph and tissue fluid.
- It is also the location where the lymphocytes are activated.
- Examples of secondary lymphoid organs include the spleen, tonsils, lymph nodes, and Peyer’s patches.