Pyramid-shaped organ in the thoracic or cervical region of mammals, composed of lymphatic tissue in which minute concentric bodies (thymic corpuscles, the remnants of epithelial structures) are found.
Notes: - Stem cells in the outer cortex of thymus develop into different kinds of T cells. Some migrate to the inner medulla and enter the bloodstream; those that do not may be destroyed to prevent autoimmune reactions.
- This organ is necessary for the development of thymus-derived lymphocytes (T cells) and is the source of several hormones involved in T-cell maturation, for example, thymosin, thymopoietin, thymulin, and thymocyte humoral factor.
- If a newborn’s thymus is removed, not enough T cells are produced, the spleen and lymph nodes have little tissue, and the immune system fails, causing a gradual, fatal wasting disease. Thymus removal in adults has little effect.
Source:
PAC, 2016, 88, 713. 'Glossary of terms used in developmental and reproductive toxicology (IUPAC Recommendations 2016)' on page 813 (https://doi.org/10.1515/pac-2015-1202)