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thymus
thy·mus T0199600 (thī′məs) n. pl. thy·mus·es 1. A small glandular organ that is situated behind the top of the breastbone, consisting mainly of lymphatic tissue and serving as the site of T cell differentiation. The thymus increases gradually in size and activity until puberty, after which it begins to atrophy. 2. A similar structure in other vertebrate animals.
[New Latin, from Greek thumos, warty excrescence, thymus.] thymus (ˈθaɪməs) n, pl -muses or -mi (-maɪ) (Physiology) a glandular organ of vertebrates, consisting in man of two lobes situated below the thyroid. In early life it produces lymphocytes and is thought to influence certain immunological responses. It atrophies with age and is almost nonexistent in the adult[C17: from New Latin, from Greek thumos sweetbread]thy•mus (ˈθaɪ məs)
n., pl. -mus•es, -mi (-mī). a ductless, butterfly-shaped gland lying at the base of the neck, formed mostly of lymphatic tissue and aiding in the production of T cells of the immune system: after puberty, the lymphatic tissue gradually degenerates. Also called thy′mus gland`. [1685–95; < New Latin < Greek thýmos] thy·mus (thī′məs) An organ in vertebrate animals located behind the top of the sternum (breastbone) where lymphocytes called T cells develop. In humans, the thymus stops growing in early childhood and gradually shrinks in size through adulthood.thymusA lymphoid endocrine gland in the chest involved in immunity.Thesaurus| Noun | 1. |  Thymus - large genus of Old World mints: thymegenus Thymusasterid dicot genus - genus of more or less advanced dicotyledonous herbs and some trees and shrubsfamily Labiatae, family Lamiaceae, Labiatae, Lamiaceae, mint family - a large family of aromatic herbs and shrubs having flowers resembling the lips of a mouth and four-lobed ovaries yielding four one-seeded nutlets and including mint; thyme; sage; rosemarythyme - any of various mints of the genus Thymus | | 2. |  thymus - a ductless glandular organ at the base of the neck that produces lymphocytes and aids in producing immunity; atrophies with agethymus glandductless gland, endocrine gland, endocrine - any of the glands of the endocrine system that secrete hormones directly into the bloodstreamimmune system - a system (including the thymus and bone marrow and lymphoid tissues) that protects the body from foreign substances and pathogenic organisms by producing the immune responsecervix, neck - the part of an organism (human or animal) that connects the head to the rest of the body; "he admired her long graceful neck"; "the horse won by a neck" |
Translationsthymus
thymus a glandular organ of vertebrates, consisting in man of two lobes situated below the thyroid. In early life it produces lymphocytes and is thought to influence certain immunological responses. It atrophies with age and is almost nonexistent in the adult Thymus (thyme), a genus of plants of the family Labiatae. The plants are subshrubs with herbaceous branches and with woody stems that are often decumbent. The small leaves are opposite and, for the most part, petioled. The flowers, which are usually lilac in color, are gathered in a head or some other type of inflorescence. The fruit consists of four nutlike lobes. There are about 400 species, distributed in the temperate zone of Eurasia and in North Africa. Of the more than 150 species found in the USSR, the most common are wild thyme (T. serpyllum) and T. marschallianus. The former is found in the forest zone, where it grows in pine forests and in arid, sandy places. The latter is encountered on slopes, along forest margins, and in glades in the forest-steppe and steppe zones. The leaves of both species contain a number of essential oils, mainly thymol, which is used as an anthelmintic, a disinfectant, and an analgesic. The liquid extract and tea from the leaves are used as expectorants. Common thyme (T. vulgaris), which grows in the Mediterranean region and is cultivated in the USSR, is used the same way as the above-mentioned species. Thyme leaves are used as a seasoning and flavoring in cooking and by the canning and alcoholic beverages industries. REFERENCEAlias lekarstvennykh rastenii SSSR. Moscow, 1962.T. V. EGOROVA thymus
thymus [thi´mus] a ductless gland lying in the upper mediastinum beneath the sternum; it reaches its maximum development during puberty and continues to play an immunologic role throughout life, even though its function declines with age. During the last stages of fetal life and the early neonatal period, the reticular structure of the thymus entraps immature stem cells arising from the bone marrow and circulating in the blood. The thymus preprocesses these cells, causing them to become sensitized and therefore capable of maturing into a specific differentiated type of lymphocyte. After sensitization by the thymus, the cells reenter the blood and are transported to developing lymphoid tissue, where they seed the cells that eventually become lymphocytes" >T lymphocytes, a type essential to the development of cell-mediated immunity. If the thymus is removed or becomes nonfunctional during fetal life, the lymphoid tissue fails to become seeded with the sensitized lymphocytes and the body's cell-mediated arm of immunity fails to develop. It is this arm of immunity that is mainly responsible for rejection of organ transplants and resistance to intracellular microbial infection, and perhaps plays a role in natural resistance to cancer. Thymus.thy·mus, pl. thy·mi, thy·mus·es (thī'mŭs, thī'mī, thī'mus-ez), [TA] [TA] A primary lymphoid organ, located in the superior and anterior mediastinum and lower part of the neck, that is necessary in early life for the normal development of immunologic function. It reaches its greatest relative weight shortly after birth and its greatest absolute weight at puberty; it then begins to involute, and much of the lymphoid tissue is replaced by fat. The thymus consists of two irregularly shaped parts united by a connective tissue capsule. Each part is partially subdivided by connective tissue septa into lobules, 0.5-2 mm in diameter, which consist of an inner medullary portion, continuous with the medullae of adjacent lobules, and an outer cortical portion. It is supplied by the inferior thyroid and internal thoracic arteries, and its nerves are derived from the vagus and sympathetic nerves. Synonym(s): thymus gland [G. thymos, excrescence, sweetbread] thymus (thī′məs)n. pl. thy·muses A small glandular organ that is situated behind the top of the breastbone, consisting mainly of lymphatic tissue and serving as the site of T cell differentiation. The thymus increases gradually in size and activity until puberty, after which it begins to atrophy.thy·mus, pl. thymi, pl. thymuses (thī'mŭs, -mī, -mŭs-ĕz) [TA] A primary lymphoid organ, located in the superior mediastinum and lower part of the neck, which is necessary in early life for the normal development of immunologic function. It reaches its greatest relative weight shortly after birth and its greatest absolute weight at puberty; it then begins to involute, and much of the lymphoid tissue is replaced by fat. The thymus consists of two irregularly shaped parts united by a connective tissue capsule. Each part is partially subdivided by connective tissue septa into lobules, which consist of an inner medullary portion, continuous with the medullae of adjacent lobules, and an outer cortical portion.
Synonym(s): thymus gland. [G. thymos, excrescence, sweetbread]thymus (thi'mus) [Gr. thymos]  THYMUSA primary lymphoid organ located in the mediastinal cavity anterior to and above the heart, where it lies over the superior vena cava, aortic arch, and trachea. The thymus comprises two fused lobes, the right larger than the left. The lobes are partially divided into lobules, each of which has an outer cortex packed with immature and developing T lymphocytes (thymocytes) and an inner medulla containing a looser arrangement of mature T lymphocytes. See: illustrationThe thymus is the primary site for T-lymphocyte differentiation; here, T lymphocytes acquire their range of antigen receptors. During the prenatal period, lymphoid stem cells migrate from the bone marrow to the thymus, filling the cortex of the lobules. Developing thymocytes acquire their characteristic CD surface antigens and their binding receptors. As the thymocytes then move from the cortex into the medulla of the lobules, some are protected but many undergo cell death in a process that culls out those reactive to autoantigens. Less than 5 % of the thymocytes mature into T cells that pass out of the lobules and migrate to the spleen, lymph nodes, and other lymphoid tissue, where they control cell-mediated immune responses. The thymus produces at least four hormones: thymopoietin, thymulin, thymus humoral factor, and the thymosins. At birth, the thymus weighs 10-15 g; by puberty, it weighs about 20 g. After this, the cortical regions of the thymus shrink and become replaced by adipose tissue, although the thymus continues to produce hormones and some thymocytes into old age. PathologyLack of a thymus or thymus hypoplasia is one component of DiGeorge syndrome, which is marked by severe lack of cell-mediated immunity; removal of the thymus of an adult is less catastrophic but leads to a less effective response to new antegens. Thymic hyperplasia results from the growth of lymph follicles containing both B lymphocytes and dendritic cells. It is found in myasthenia gravis and, occasionally, in other autoimmune diseases (e.g., Graves' disease, rheumatoid arthritis, and systemic lupus erythematosus). Thymomas involve only the thymic epithelial cells. Other tumors, including those associated with Hodgkin's disease and lymphomas, involve thymocytes. accessory thymusA lobule isolated from the mass of the thymus gland. It is also called a supernumerary thymus. Synonym: supernumerary thymuspersistent hyperplastic thymusThymus persisting into adulthood, sometimes hypertrophying.supernumerary thymusAccessory thymus.thymus A small flat organ of the lymphatic system situated immediately behind the breastbone, that is apparent in children but inconspicuous after puberty. The thymus processes primitive LYMPHOCYTES so that they differentiate into the T cells of the immune system. It also differentiates T cells into T1 and T2 classes, a process that is influenced by the early environment of the individual.thymus an endocrine gland situated in the neck region of most vertebrates, but close to the heart in mammals. It produces LYMPHOCYTES which then move to lymph nodes. The thymus produces a hormone called thymosin which causes the lymphocytes to form ANTIBODY-producing plasma cells immediately after birth, but regresses in adult animals.ThymusAn organ near the base of the neck that produces cells that fight infection. It is at its largest at puberty, then declines in size and function during adult life.Mentioned in: Ataxia-Telangiectasia, Lymph Node Biopsy, Mediastinoscopythy·mus, pl. thymi, pl. thymuses (thī'mŭs, -mī, -mŭs-ĕz) [TA] A primary lymphoid organ, located in the superior mediastinum and lower part of the neck, which is necessary in early life for the normal development of immunologic function. [G. thymos, excrescence, sweetbread]AcronymsSeeTThymus
Synonyms for Thymusnoun large genus of Old World mints: thymeSynonymsRelated Words- asterid dicot genus
- family Labiatae
- family Lamiaceae
- Labiatae
- Lamiaceae
- mint family
- thyme
noun a ductless glandular organ at the base of the neck that produces lymphocytes and aids in producing immunitySynonymsRelated Words- ductless gland
- endocrine gland
- endocrine
- immune system
- cervix
- neck
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