Cell and Tissue Research

, Volume 218, Issue 3, pp 475–485 | Cite as

Specializations for excitation-contraction coupling in the podial retractor cells of the starfish Stylasterias forreri

  • Michael J. Cavey
  • Richard L. Wood


Ultrastructural examination of the podium of the asteroid echinoderm Stylasterias forreri has revealed that cells of the coelomic epithelium and cells of the retractor muscle should be considered as components of a single epithelium. The podial retractor cells are, therefore, myoepithelial in nature. This report concentrates on those ultrastructural features of the retractor cells that are most likely involved with excitation-contraction coupling. The spatial arrangement of the sarcoplasmic reticulum, the couplings between the sarcoplasmic reticulum and sarcolemma, and an intramembranous specialization of the sarcolemma are documented and discussed. Current concepts regarding the innervation of the retractor cells of the podium and the protractor cells of the ampulla are reviewed, and specific proposals for further investigation of podial innervation are outlined.

Key words

Excitation-contraction coupling Podium Retractor cells Starfish Ultrastructure 


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Copyright information

© Springer-Verlag GmbH & Co. KG 1981

Authors and Affiliations

  • Michael J. Cavey
    • 1
    • 2
  • Richard L. Wood
    • 1
    • 2
  1. 1.Department of Biology, Faculty of ScienceUniversity of CalgaryCalgaryCanada
  2. 2.Department of AnatomySchool of Medicine, University of Southern CaliforniaLos AngelesUSA

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