Final answer:
The C. thymus is the lymphoid organ necessary for the selection and maturation of T lymphocytes for the immune system, critical for identifying self from non-self cells, and ensuring a proper adaptive immune response.
Step-by-step explanation:
The lymphoid organ required for the selection of a functional population of T lymphocytes (T cells) for the immune system is the thymus. The thymus is a primary lymphoid organ, along with bone marrow. While bone marrow is the site where all lymphocytes are produced and where B cells mature, the thymus is the organ where T cells undergo maturation. This maturation process includes learning to distinguish self from non-self cells, crucial for providing an adaptive immune response without harming the body's own cells.
The thymus gland is particularly active during infancy and childhood, playing a key role in the development of the immune system. It has been estimated that thymic selection eliminates 98% of thymocytes, with the remaining 2% exiting the thymus and migrating to secondary lymphoid organs like lymph nodes, spleen, and tonsils. These mature naive T cells remain in these secondary organs until they are activated through the presentation of specific antigens.
Secondary lymphoid organs, which include the tonsils, spleen, and lymph nodes, do not produce or mature lymphocytes but are sites where lymphocytes are activated to respond to pathogens. They filter lymph and blood, detect infections, and store lymphocytes, aiding in the adaptive immune response.