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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.
The thymus may contain cysts, usually less than 4 cm in diameter. Thymic cysts are usually detected incidentally and do not generally cause symptoms. [3] Thymic cysts can occur along the neck or in the chest (mediastinum). [26] Cysts usually just contain fluid and are lined by either many layers of flat cells or column-shaped cells. [26]
Thymic epithelial cells (TECs) are specialized cells with high degree of anatomic, phenotypic and functional heterogeneity that are located in the outer layer (epithelium) of the thymic stroma. The thymus , as a primary lymphoid organ , mediates T cell development and maturation.
In 1989, two scientific groups came up with the hypothesis that the thymus expresses genes which are in the periphery, strictly expressed by specific tissues (e.g.: Insulin produced by β cells of the pancreas) to subsequently present these so-called "tissue-restricted antigens" (TRAs) from almost all parts of the body to developing T cells in order to test which TCRs recognize self-tissues ...
Histology of the thymus showing the cortex and medulla Minute structure of thymus. The ability of T cells to recognize foreign antigens is mediated by the T cell receptor (TCR), which is a surface protein able to recognize short protein sequences ( peptides ) that are presented on MHC .
The blood–thymus barrier regulates exchange of substances between the circulatory system and thymus, providing a sequestered environment for immature T cells to develop. The barrier also prevents the immature T cells from contacting foreign antigens (since contact with antigens at this stage will cause the T cells to die by apoptosis ).
Cortical thymic epithelial cells (cTECs) form unique parenchyma cell population of the thymus which critically contribute to the development of T cells. Thymus tissue is compartmentalized into cortex and medulla and each of these two compartments comprises its specific thymic epithelial cell subset. cTECs reside in the outer part- cortex, which ...
Tactile corpuscles or Meissner's corpuscles are a type of mechanoreceptor discovered by anatomist Georg Meissner (1829–1905) and Rudolf Wagner. [ 1 ] [ 2 ] This corpuscle is a type of nerve ending in the skin that is responsible for sensitivity to pressure .