BIOC39H3 Lecture Notes - Lecture 15: Thymocyte, Progenitor Cell, Interleukin 7
8 Apr 2015
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Document Summary
Progenitors develop in the bone marrow and migrate to thymus. Mature t cell migrate to secondary lymphoid organs. Activated t cell migrate to site of infection. A lymphoid organ in the upper anterior thorax just above the heart. Dedicated to t cell development and contains immature t cells called thyomcytes, which are embedded in a network of epithelial cells called the thymic stroma. Does not receive lymph from other tissues. The blood is the only route by with progenitors enter the thymus and mature t cells leave. Cortex: immature thymocytes, branched cortical epithelial cells and a few macrophages. Medulla: mature thymocytes, medullary epithelial cells, dendritic cells and macrophages. Hassall"s corpuscles: sites of cell destruction, macrophages remove the many thymocytes that fail to mature properly. The human thymus is fully developed before birth and by one year after birth it begins to degenerate, with fat gradually claiming the areas once packed with thymocytes.
