<Tr> <Th> FMA </Th> <Td> 9609 </Td> </Tr> <Tr> <Td_colspan="2"> Anatomical terminology (edit on Wikidata) </Td> </Tr> <P> The thymus is a specialized primary lymphoid organ of the immune system . Within the thymus, T cells mature . T cells are critical to the adaptive immune system, where the body adapts specifically to foreign invaders . The thymus is composed of two identical lobes and is located anatomically in the anterior superior mediastinum, in front of the heart and behind the sternum . Histologically, each lobe of the thymus can be divided into a central medulla and a peripheral cortex which is surrounded by an outer capsule . The cortex and medulla play different roles in the development of T cells . Cells in the thymus can be divided into thymic stromal cells and cells of hematopoietic origin (derived from bone marrow resident hematopoietic stem cells). Developing T cells are referred to as thymocytes and are of hematopoietic origin . Stromal cells include epithelial cells of the thymic cortex and medulla, and dendritic cells . </P> <P> The thymus provides an inductive environment for development of T cells from hematopoietic progenitor cells . In addition, thymic stromal cells allow for the selection of a functional and self - tolerant T cell repertoire . Therefore, one of the most important roles of the thymus is the induction of central tolerance . </P>

Where is the thymus gland located in the human body