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The thymus (pl.: thymuses or thymi) is a specialized primary lymphoid organ of the immune system.Within the thymus, thymus cell lymphocytes or T cells mature. T cells are critical to the adaptive immune system, where the body adapts to specific foreign invaders.
TECs, as a component of the thymus, play a key role in thymocyte development and self-tolerance, so their dysfunction causes many autoimmune diseases, tumors of immunodeficiencies. Most frequently are occurred epithelial tumors established from TEC and thymocytes - thymomas and thymic carcinoma.
The thymus is where the T lymphocytes mature and become immunocompetent. The loss or lack of the thymus results in severe immunodeficiency and subsequent high susceptibility to infection. In most species, the thymus consists of lobules divided by septa which are made up of epithelium which is often considered an epithelial organ.
Hassall's corpuscles (also known as thymic bodies) are structures found in the medulla of the human thymus, formed from eosinophilic type VI thymic epithelial cells arranged concentrically. These concentric corpuscles are composed of a central mass, consisting of one or more granular cells, and of a capsule formed of epithelioid cells.
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.
The thymus contributes fewer cells as a person ages. As the thymus shrinks by about 3% [ 15 ] a year throughout middle age, a corresponding fall in the thymic production of naive T cells occurs, leaving peripheral T cell expansion and regeneration to play a greater role in protecting older people.
Thymic involution is the shrinking of the thymus with age, resulting in changes in the architecture of the thymus and a decrease in tissue mass. [1] Thymus involution is one of the major characteristics of vertebrate immunology, and occurs in almost all vertebrates, from birds, teleosts, amphibians to reptiles, though the thymi of a few species of sharks are known not to involute.
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