| 释义 |
islet|ˈaɪlɪt|
Also 6 islette.
[a. F. islette, mod.F. îlette, dim. of isle n.: see -et1. See also islot, isolet.]
1. A little island, an eyot or ait.
1538Leland Itin. II. 58, I passid over Frome Water,..where the water brekith into Armelettes and makith Islettes. 1610Holland Camden's Brit. ii. 219 Shetland is an Isle..environed with other Islets. 1774Goldsm. Nat. Hist. (1776) VI. 118 Where there is an islet in the stream. 1859Jephson Brittany vii. 89 A little islet on the coast still bears the name of Avalon.
fig.1883Stevenson Silverado Squatters 228 Mere islets of business in a sea of sunny day-time.
2. transf.
a. Something resembling an island in position; a small piece of land markedly differing in character from that by which it is surrounded, as a wooded eminence in a marsh or plain; any isolated tract or spot; = island n. 2 a. Also = island n. 2 d.
1645Boate Irel. Nat. Hist. (1652) 111 Little Tufts or Ilets..consisting of Reeds, Rushes, high sower Grass,..a few feet in compass;..These little Ilets of Tufts being..spread over all the Bog. 1791W. Bartram Carolina 140 Expansive green meadows or savannas, in which are to be seen..islets of Oak and Bays. 1826Kirby & Sp. Entomol. IV. 286 Islet.., a spot of a different colour, included in a plaga or macula. Ex. The Ocelli in the Primary Wings of Hipparchia Semele. 1860Tyndall Glac. i. iii. 27 An islet of stones and débris, where we paused to rest ourselves. 1864Tennyson Aylmer's F. 65 A but less vivid hue Than of that islet in the chestnut-bloom Flamed in his cheek. 1871E. F. Burr Ad Fidem xv. 308 Those islets of light which roam so mazily in the dark deeps. 1921Discovery Oct. 257/2 A dozen guiding marks, consisting of the beginnings of lines, bifurcations and islets.
b. An isolated piece of animal or vegetable tissue. islet (or Islet) of Langerhans [tr. F. îlot de Langerhans (E. Laguesse 1893, in Compt. rend. hebdom. d. Séances et Mém. de la Soc. de Biol. XLV. 819): named after Paul Langerhans (1847–1888), German anatomist, who, in 1869, first described such islets], any of numerous highly vascular islets of tissue in the pancreas, composed of light-staining cells of two principal types, one of which secretes insulin and the other glucagon; also ellipt.
1851Carpenter Man. Phys. 164 The temporary Cartilages..are equally destitute of vessels when their mass is small; but if their thickness exceed an eighth of an inch, they are permeated by canals for the transmission of vessels. Still these vessels do not ramify with any minuteness in the tissue; and they leave large islets, in which the nutritive process must take place on the plan just described. 1884Bower & Scott De Bary's Phaner. 499 Especially in their [the Caryophylleæ] rhizomes, thin-walled, long-celled parenchyma, often forming large irregular islets or annular segments, is inserted between fibrous masses of similar form. 1896Jrnl. R. Microsc. Soc. 35 Besides the solid buds which form the first ‘islets of Langerhans’, they give rise to numerous hollow buds. 1897Allbutt's Syst. Med. III. 955 The ulceration is so extensive that only islets of mucous membrane are left here and there. 1898Ibid. V. 204 Islets of spongy tissue separate the individual nodules [of tubercle]. 1904Proc. R. Soc. LXXIII. 84 The degeneration or absence of the islets in diabetes. 1910Practitioner Jan. 32 Many other pathological conditions..have been ascribed to abnormalities of other ductless glands; e.g...glycosuria to the loss of the internal secretion formed by the islets of Langerhans in the pancreas. 1968Times 27 Nov. 9/3 Those parts of the organ [sc. the pancreas] concerned with carbohydrate metabolism—known as the islets of Langerhans. 1973Nature 23 Mar. 259 Yields of up to 350 Islets per rat pancreas have been achieved using this method.
3. attrib.
1810Scott Lady of L. iii. iii, Abrupt he paced the islet strand. 1861Sat. Rev. XII. 388/1 St. Helier, too, has its islet-castle, built by Queen Elizabeth. Ibid. 388/2 An islet-breakwater. Ibid. 389/1 An islet-rock. 1871R. Ellis Catullus xxviii. 12 Was only this the plea Detain'd you in that islet angle of the west? 1879C. Geikie Christ xxix. 335 Constellations anchored on the vast expanse like tiny islet clusters on the boundless ocean. 1899Westm. Gaz. 2 Oct. 10/1 Signalling from lightships and islet lighthouses to the mainland. 1914, etc. Islet-tissue [see insulin 1]. 1927Haldane & Huxley Animal Biol. xii. 279 Islet cell of human pancreas. 1962Lancet 12 May 1003/2 The characteristics of the Zollinger–Ellison syndrome are extreme gastric hyper⁓secretion, intractable peptic ulceration..and either hyperplasia or tumour of the islet-cells of the pancreas. 1963E. J. W. Barrington Introd. Gen. & Compar. Endocrinol. iii. 43 We have evidence that islet tissue arose very early in vertebrate evolution. 1965Lee & Knowles Animal Hormones vii. 113 Occasionally in man a tumour of the islet cell occurs and there is excessive secretion of insulin. |