Cell and Tissue Research

, Volume 226, Issue 3, pp 675–687

The giant neurone system in ophiuroids

III. The detailed connections of the circumoral nerve ring
  • J. L. S. Cobb
  • T. R. Stubbs

DOI: 10.1007/BF00214794

Cite this article as:
Cobb, J.L.S. & Stubbs, T.R. Cell Tissue Res. (1982) 226: 675. doi:10.1007/BF00214794


The morphology of the circumoral nerve ring of an ophiuroid, Ophiura texturata, is described. Particular attention is given to a system of fibres which are giant by echinoderm standards, and which occur both in the ectoneural and hyponeural parts of the nerve ring. The giant fibres in the ectoneural tissue do not show the complicated pattern of distribution present in the segmental ganglia of the radial nerves. The main areas of neuropil in the ectoneural tissue are associated with small axon bundles which leave the nerve ring to innervate the gut and disc. The hyponeural tissue is exclusively motor and is involved in the innervation of the main radial and inter-radial muscles of the disc. Branches of the motor nerves are also associated with juxtaligamental tissue, the secretory products from which are thought to influence the plasticity of collagenous connective tissue. The structure of the circumoral nerve ring suggests that it serves as a functional connection between the nerve cords in adjacent radii. The ultrastructural evidence does not support the view that the circumoral nerve ring represents a central nervous system.

Key words

Giant neurone Circumoral nerve ring Ophiuroidea Echinodermata 

Copyright information

© Springer-Verlag 1982

Authors and Affiliations

  • J. L. S. Cobb
    • 1
  • T. R. Stubbs
    • 1
  1. 1.Gatty Marine LaboratorySt. AndrewsUK
  2. 2.Gatty Marine Laboratory, The UniversitySt. AndrewsScotland

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