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The purpose of thymocyte development is to produce mature T cells with a diverse array of functional T cell receptors, through the process of TCR gene rearrangement. Unlike most genes, which have a stable sequence in each cell which expresses them, the T cell receptor is made up of a series of alternative gene fragments. In order to create a ...
This process continues into old age, where whether with a microscope or with the human eye, the thymus may be difficult to detect, [4] although typically weighs 5–15 grams. [3] Additionally, there is an increasing body of evidence showing that age-related thymic involution is found in most, if not all, vertebrate species with a thymus ...
A figure depicting the process of T cell / thymocyte positive and negative selection in the thymus. cTEC shown in yellow. Cortical thymic epithelial cells (cTECs) form unique parenchyma cell population of the thymus which critically contribute to the development of T cells.
A figure depicting the process of T cell / thymocyte positive and negative selection in the thymus. mTEC shown in orange. Medullary thymic epithelial cells (mTECs) represent a unique stromal cell population of the thymus which plays an essential role in the establishment of central tolerance.
The most important transcription factor for all stages of TEC development in embryonic and postnatal thymus is a Foxn1. Foxn1 controls the whole process by the activation of its target genes with binding to specific DNA sequence via its forkhead box domain. There are highlighted over 400 Foxn1 targeted genes, included critical loci for TEC ...
A thymocyte can only become an active T cell when it survives the process of developing a functional TCR. The TCR consists of two major components, the alpha and beta chains. These both contain random elements designed to produce a wide variety of different TCRs, but due to this huge variety they must be tested to make sure they work at all.
The process is a defining feature of the adaptive immune system. V(D)J recombination in mammals occurs in the primary lymphoid organs ( bone marrow for B cells and thymus for T cells) and in a nearly random fashion rearranges variable (V), joining (J), and in some cases, diversity (D) gene segments.
Thymus stromal cells are subsets of specialized cells located in different areas of the thymus. [1] They include all non-T-lineage cells, such as thymic epithelial cells (TECs), endothelial cells, mesenchymal cells, dendritic cells, and B lymphocytes, and provide signals essential for thymocyte development and the homeostasis of the thymic stroma.