trocho-
(trɒkəʊ)
before a vowel troch- (trɒk), combining form repr. Gr. τροχός wheel, disk; occurring in several scientific words. trocheidoscope (-ˈkaɪdəskəʊp) [after kaleidoscope n.], a rotating disc with coloured sectors, for showing combinations of colours (Cassell's Encycl. Dict. 1888). trochelminth (ˈtrɒkɛlmɪnθ) [Gr. ἕλµινς, ἑλµινθ- worm], a rotifer. ˈtrochoblast [Gr. βλαστός germ], one of the embryonic cells giving rise to the prototroch in the trochophore larva of marine annelids. ˌtrochoceˈphalic (-sɪˈfælɪk) a. [Gr. κεϕαλή head], having a round form of skull due to permature union of the parietal and frontal bones; so trochocephaly (-ˈsɛfəlɪ), the condition of being trochocephalic. trochoceracone (-ˈsɛrəkəʊn) [Gr. κέρας horn, κῶνος cone], a nautiloid shell with loose flattened coils, as those of the fossil genus Trochoceras; so trochoceran (trəʊˈkɒsərən) a., having the form or character of such a shell (Cent. Dict. Suppl.). ˌtrochocœlomate (-sɪˈləʊmət) a., belonging to the Trochocœlomata, a proposed division of Metazoa, containing animals having radiated cœlomes (= radiata). troˈchometer [-meter] = trechometer (Worcester 1846). ˈtrochophore (-fɔə(r)) [Gr. -ϕόρος bearing], ˈtrochosphere (-sfɪə(r)), a larval form constituting a stage in the development of most molluscs and of certain worms, esp. marine annelids, characterized by a spheroidal body with a ring of cilia; also attrib.; hence trochospheric (-ˈsfɛrɪk), -ˈspherical adjs., pertaining to or having the form of a trochosphere. trochozoon (-ˈzəʊɒn) [Gr. ζῷον animal], one of the Trochozoa, a collective name for those molluscs, annelids, etc. which pass through a trochosphere larval stage, or for such larvæ; also for a hypothetical ancestral group of animals from which these are assumed to be derived.
| 1904 Amer. Nat. July–Aug. 500 Cells..identical in origin with the ‘primary *trochoblasts’ of the annelids. |
| 1878 Bartley tr. Topinard's Anthrop. v. 176 *Trochocephalic, very round skull. |
| Ibid. Index 547/1 *Trochocephaly. |
| 1884 Hyatt in Proc. Boston Soc. Nat. Hist. 5 Mar. 113 We can readily transform a protocoelomate into a *trochocoelomate by destroying the horizontal parts of the partitions between the ampullae. |
| 1892 J. A. Thomson Outlines Zool. xi. 182 By far the most important larval form among Annelids is that known as the Trochosphere or *Trochophore. 1909 J. W. Jenkinson Experim. Embryol. 213 Eight instead of the usual four macromeres were found in the Trochophore larva. |
| 1883 E. R. Lankester in Encycl. Brit. XVI. 648/1 [In the Limpet the] Diblastula..acquires a ciliated band, and becomes a nearly spherical *Trochosphere. 1888 Rolleston & Jackson Anim. Life 454 The Mollusca with the exception of Cephalopoda pass through a typical larval development, in two stages—a Trochosphere and a Veliger stage. |
| 1899 Syd. Soc. Lex., *Trochospheric. |
| 1891 Cent. Dict., *Trochospherical. |
| 1890 Nature 22 May 94/1 The author's conclusions are, that the Balanoglossus..has originated from a *trochozoon which acquired some features in common with worms. |