Final answer:
Committed lymphocyte progenitors originate in the bone marrow. B cells mature in the bone marrow while T cells migrate to the thymus for maturation. The bone marrow and thymus are primary lymphoid organs essential for the development of lymphocytes.
Step-by-step explanation:
Committed lymphocyte progenitors originate in the bone marrow. Both B cells and T cells are lymphocytes that play crucial roles in the immune system. B cells, named for their site of maturation in the bone marrow, remain there to mature, while T cell progenitors migrate from the bone marrow to the thymus to complete their development. This migration is essential for the specialization of T cells, which become adept at recognizing and responding to pathogens as part of the body's adaptive immune response.
The thymus is where T cells acquire their defining characteristics, such as their T cell receptors. After leaving the thymus, they are ready to patrol the body and defend against infections. The bone marrow and thymus are known as primary lymphoid organs due to their roles in lymphocyte development. In contrast, lymphoid tissues such as the spleen and lymph nodes are sites where mature lymphocytes can encounter antigens and become activated.