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The thymus facilitates the maturation of T cells, an important part of the immune system providing cell-mediated immunity. [11] T cells begin as hematopoietic precursors from the bone-marrow, and migrate to the thymus, where they are referred to as thymocytes.
In birds and mammals, bone marrow is the primary site of new blood cell production (or haematopoiesis). [3] It is composed of hematopoietic cells, marrow adipose tissue, and supportive stromal cells. In adult humans, bone marrow is primarily located in the ribs, vertebrae, sternum, and bones of the pelvis. [4]
When bone marrow develops, it eventually assumes the task of forming most of the blood cells for the entire organism. [3] However, maturation, activation, and some proliferation of lymphoid cells occurs in the spleen, thymus, and lymph nodes. In children, haematopoiesis occurs in the marrow of the long bones such as the femur and tibia.
The primary (or central) lymphoid organs, including the thymus, bone marrow, fetal liver and yolk sac, are responsible for generating lymphocytes from immature progenitor cells in the absence of antigens. [12] The thymus and the bone marrow constitute the primary lymphoid organs involved in the production and early clonal selection of ...
When bone marrow develops, it eventually assumes the task of forming most of the blood cells for the entire organism. [3] However, maturation, activation, and some proliferation of lymphoid cells occurs in the spleen, thymus, and lymph nodes. In children, haematopoiesis occurs in the marrow of the long bones such as the femur and tibia.
Thymocyte. A thymocyte is an immune cell present in the thymus, before it undergoes transformation into a T cell. [1] Thymocytes are produced as stem cells in the bone marrow and reach the thymus via the blood. Thymopoiesis describes the process which turns thymocytes into mature T cells according to either negative or positive selection.
T cells are born from hematopoietic stem cells, [1] found in the bone marrow. Developing T cells then migrate to the thymus gland to develop (or mature). T cells derive their name from the thymus. [2] [3] After migration to the thymus, the precursor cells mature into several distinct types of T cells. T cell differentiation also continues after ...
T cells are formed in bone marrow and then migrate to the cortex of the thymus to undergo maturation in an antigen-free environment for about one week where a mere 2–4% of the T cells succeed. The remaining 96–98% of T cells die by apoptosis and are phagocytosed by macrophages in the thymus.