Cell and Tissue Research

, Volume 304, Issue 2, pp 165–174

The unusual cartilaginous tissues of jawless craniates, cephalochordates and invertebrates

  • Glenda M. Wright
  • Fred W. Keeley
  • Paul Robson

DOI: 10.1007/s004410100374

Cite this article as:
Wright, G., Keeley, F. & Robson, P. Cell Tissue Res (2001) 304: 165. doi:10.1007/s004410100374


A collagenous extracellular matrix was previously considered to be a requirement for classification of true cartilage. Data from the lamprey and hagfish now clearly indicate that both of these jawless craniates have extensive non-collagenous, yet cartilaginous endoskeletons. Non-collagenous cartilages are present in the cephalochordates (amphioxus) and in the invertebrates, although collagen-containing cartilages also are found in the invertebrates. This review summarizes current knowledge of the morphological, biochemical and molecular characteristics of the unusual non-collagenous cartilages in jawless craniates and the cartilaginous tissues in amphioxus and invertebrates. A least two types of non-collagenous cartilage matrix proteins are found in both the hagfishes and the lampreys, all of which are resistant to digestion by cyanogen bromide (CNBr). Although all four of these matrices show some similarities with each other, suggesting a family of non-collagenous, elastin-like proteins, it is clear that the major matrix proteins of each are different. New morphological and biochemical information on the cartilaginous tissues in squid, horseshoe crab and amphioxus reveals the presence of CNBr-insoluble, non-collagenous matrix proteins, potentially extending the jawless craniate family of cartilaginous proteins into the invertebrates. Details of the evolutionary relationships between these non-collagenous matrix proteins and the significance of the occurrence of these proteins as the major components of the cartilaginous tissues of jawless craniates, amphioxus, horseshoe crab and squid, all of which are capable of producing a variety of collagens in other tissues, remain to be investigated.

Cartilage Non-collagenous Hagfish Lamprey Amphioxus Horseshoe crab Squid Evolution Endoskeleton

Copyright information

© Springer-Verlag 2001

Authors and Affiliations

  • Glenda M. Wright
    • 1
  • Fred W. Keeley
    • 2
  • Paul Robson
    • 3
  1. 1.Department of Anatomy and Physiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown, Prince Edward Island, Canada, C1A 4P3
  2. 2.Division of Cardiovascular Research, Research Institute, Hospital for Sick Children and the Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada, M5G 1X8
  3. 3.Division of Cardiology, Joseph Stokes Research Institute, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA