‖ thymus
(ˈθaɪməs)
Pl. thymi (ˈθaɪmaɪ).
[mod.L., a. Gr. θύµος (θῠ-) a warty excrescence; also the thymus gland (Galen).]
1. a. Anat. A glandular body of obscure function (one of the so-called ‘ductless glands’) situated near the base of the neck in vertebrate animals; in man usually disappearing after the period of childhood.
In the calf and lamb called by butchers sweetbread, or more precisely neck or throat sweetbread, for distinction from the pancreas or stomach sweetbread.
| 1693 tr. Blancard's Phys. Dict. (ed. 2), Thymus, a Glandule in the Throat, which separates watry Humour, called Lympha from the Blood, and empties it by the Lymphatick Vessels. 1704 J. Harris Lex. Techn. I, Thymus, is a conglobate Glandule in the Throat, growing to the upper part of the Mediastinum, and seated between the Divisions of the Subclavian Veins and Arteries. 1713 Cheselden Anat. iii. xi. (1726) 232 Just within the Thorax is seated another [gland] called Thymus. 1868 Owen Vertebr. Anim. xxxii. III. 567 The thymus in Monotremes lies between the episternum and the beginnings of the vessels from the aortic arch. 1881 Mivart Cat 237 The thymus..is of very large size during immaturity. 1888 Rolleston & Jackson Anim. Life 350 The thymus atrophies in the higher Vertebrata as a rule. 1899 Allbutt's Syst. Med. VI. 89 Several instances of enlarged thymus have been reported of late years. 1904 Brit. Med. Jrnl. 10 Sept. 603 It is possible..that a similar extract prepared from human thymi would have a depressor action. |
b. Now usually
thymus gland (rarely
thymus body).
| 1776 M. Falconer (title) An Account of the Structure and Offices..of the Thymus Glands. 1797 M. Baillie Morb. Anat. (1807) 111 The thymus gland is subject to few diseases, and is only of temporary existence. 1847 Youatt Horse xi. 231 It is ‘the thymus gland’, or, in vulgar language, the sweet-bread. 1862 Miller Elem. Chem. III. 722 Hypoxanthine has also been found in the thyroid or thymus glands. 1899 Allbutt's Syst. Med. VI. 73 Abscesses beginning in the thymus body. |
c. thymus nucleic acid = thymonucleic acid s.v. thymonucleic a. Now
Hist. † 2. Path. A rugose wart resembling a bud of thyme.
Obs.| 1693 tr. Blancard's Phys. Dict. (ed. 2), Thymus,..also a fleshy Tumor that hangs upon the Body like a Wart, of a colour like the Flower of Time. 1811 in Hooper Med. Dict. |
3. Comb., as
thymus-dependent,
thymus-derived,
thymus-independent adjs.| 1963 Jrnl. Nat. Cancer Inst. XXXI. 1466 In the thymectomized newborn mouse..re-establishment of immunologic competence..is also known to be thymus-dependent. 1977 Proc. R. Soc. Med. LXX. 524/2 This change may be responsible for the diminished response to thymus-dependent antigens that is seen in subjects with chronic liver disease. |
| 1970 New Scientist 7 May 271/2 The thymus-derived T cells apparently move through the body more actively than the B cells. 1974 Ciba Symposium XX. 114 They suggest that, by one means or another, trypanosome infections break the control link between thymus-dependent lymphocytes (T cells) and thymus-independent lymphocytes (B cells). |