单词 | mesomere |
释义 | mesomeren. 1. Zoology. Each of a series of axial elements in the primitive vertebrate fin (archipterygium) or forelimb. ΚΠ 1876 T. H. Huxley in Proc. Zool. Soc. 4 Jan. 53 Analogy leads to the suspicion that a still more archaic fish than Ceratodus would have as many pairs of rays as median pieces. In this condition the skeleton would be made up of homologous segments, which might be termed pteromeres, each of which would consist of a mesomere with a præaxial and a postaxial paramere. 1888 Amer. Naturalist 22 362 The basal mesomere of the Ceratodus fin may conceivably have been derived from the metapterygium. 1951 Amer. Midland Naturalist 46 250 The skeletal plan of the crossopterygian paired fins and of the primitive tetrapod limb is interpreted as an axial series of bones (mesomeres), each with one or more obliquely placed pre-axials (radials). 1981 Systematic Zool. 30 383/2 The pelvic [fin in Eusthenopteron] includes fewer elements (‘mesomeres’) than the pectoral. ΚΠ 1897 A. T. Masterman in Q. Jrnl. Microsc. Sci. 40 330 The body is divided into three archimeric segments, the protomere, the paired mesomeres, and the metamere. 3. Embryology. A mesodermal segment or somite; a protovertebra. Also: the middle region of the mesoderm. ΘΚΠ the world > life > biology > biological processes > procreation or reproduction > embryo or fetus > embryo parts > [noun] > regions segment1826 lateral plate1859 protovertebra1869 mesomere1902 organizator1924 organizer1925 field1927 organization centre1928 inductor1929 1902 Webster's Internat. Dict. Eng. Lang. Suppl. Mesomere, (a) a provertebra, or mesoblastic somite. 1915 Proc. Royal Soc. 1914–15 B. 88 474 The cartilaginous visceral arches and their equivalents in the primordial skull are branchiomeric organs, and have no genetic relation to the mesomeres. 1920 I. F. Henderson & W. D. Henderson Dict. Sci. Terms 184/2 Mesomere, the middle zone of the coelomic pouches in the embryo. 1977 T. I. Storer et al. Elements Zool. (ed. 4) x. 147/2 A third portion (mesomere) is the forerunner of the excretory system and parts of the reproductive system. 1999 Developmental Biol. 210 381 There is no evidence in vertebrate embryos for the presence of preotic myotomes. We conclude that mesomere-based theories of head metamerism are inappropriate. 4. Embryology. A blastomere of medium size, produced by some forms of embryonic cleavage. Cf. macromere n., micromere n. ΚΠ 1902 Webster's Internat. Dict. Eng. Lang. Suppl. Mesomere.., (b) a blastomere of medium size. 1910 Science 25 Mar. 464/1 During the cleavage the clear-gray substance goes into the three quartets of ectomeres, the yellow material into the entomeres and mesomeres. 1966 Science 11 Mar. 1233/2 The upper four cells divide equally and meridionally to form a layer of eight mesomeres. 1975 Nature 27 Nov. 343/2 Dissociation of embryos at this cell stage yields three cell types which are easily distinguishable by size: micromeres, mesomeres and macromeres. 1992 Analyt. Biochem. 203 22 Using this method, we fractionated the three different blastomere types of the 16-cell sea urchin embryo, the micromeres, mesomeres, and macromeres. This entry has been updated (OED Third Edition, September 2001; most recently modified version published online March 2022). < n.1876 |
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