Where do T cells mature?

Where do T cells mature?

• A. Bone marrow
• B. Thymus
• C. Spleen
• D. Lymph nodes

Answer: (B)

T cell maturation occurs in the thymus. Lymphoid precursors originate in the bone marrow, but they travel to the thymus where they complete their development. In the thymus, developing T cells (thymocytes) undergo crucial selection processes: positive selection in the cortex ensures cells can recognize self-MHC, and negative selection in the medulla eliminates those that react strongly to self-antigens. This education results in mature T cells that exit to the periphery as helper or cytotoxic T cells, equipped to respond to foreign antigens while maintaining self-tolerance. The bone marrow is where lymphoid progenitors begin and where B cells mature, while the spleen and lymph nodes are secondary lymphoid organs where mature T cells encounter antigens and become activated—they do not complete maturation there.

T cell maturation occurs in the thymus. Lymphoid precursors originate in the bone marrow, but they travel to the thymus where they complete their development. In the thymus, developing T cells (thymocytes) undergo crucial selection processes: positive selection in the cortex ensures cells can recognize self-MHC, and negative selection in the medulla eliminates those that react strongly to self-antigens. This education results in mature T cells that exit to the periphery as helper or cytotoxic T cells, equipped to respond to foreign antigens while maintaining self-tolerance. The bone marrow is where lymphoid progenitors begin and where B cells mature, while the spleen and lymph nodes are secondary lymphoid organs where mature T cells encounter antigens and become activated—they do not complete maturation there.