Online Dictionary of Invertebrate Zoology: Complete Work - Best Text

176Maggenti and Gardnercentral region (ARTHRO: Insecta) The costal region of a wing.central symmetry system (ARTHRO: Insecta) The medianfield of the moth wing pattern delimited basally and distallyby the light central line of the transverse, anterior andposterior lines.central tube (NEMATA) The sclerotized cylindrical axis of thehead skeleton of nematodes, through which the stylet extendsduring feeding.centric fusion The fusion of two acrocentric chromosomes toform a single metacentric chromosome through translocationand as a rule, the loss of a centromere.centrifugal a. [Gr. kentron, center; L. fugare, to flee] 1.Turning from or being thrown away from the center. 2.Moving toward the periphery, as nerve impluses.centriole n. [Gr. kentron, center] Either of the two minutespherical bodies in a cell center that migrates to oppositepoles during cell division and serves to organize the alignmentof the spindles.centripetal a. [Gr. kentron, center; L. petere, to move toward]Turning inwardly from the outside or periphery; toward thecenter. see centrifugal.centripetal canal (CNID) One of numerous blind canals runningfrom the circular canal toward the apex of the bell incertain jellyfish.centris n. [L. centrum, sting] (ARTHRO: Insecta) In Hymenoptera,the sting.centrodorsal a. [Gr. kentron, center; L. dorsum, back] 1. Referringto central and dorsal. 2. (ECHINOD: Crinoidea) Pertainingto a cirriferous ossicle, fused or semifused, attachedto the theca.centrogenous a. [Gr. kentron, center; gennaein, to produce]1. Growing from the center. 2. (PORIF) A spicule growingfrom a common center.centrolecithal egg (ARTHRO) A type of arthropod egg in whichthe nucleus is located centrally in a small amount of nonyolkycytoplasm surrounded by a large mass of yolk untilfertilized; when nuclear divisions begin the nuclei migrate