Cell and Tissue Research

, Volume 239, Issue 2, pp 455–458 | Cite as

Demonstration of the granular layer and the fate of the hyaline layer during the development of a sea urchin (Lytechinus variegatus)

  • R. Andrew Cameron
  • Nicholas D. Holland


Employing electron-microscopic methods that help retain polyanionic materials, we describe the extracellular coverings of a sea urchin (Lytechinus variegatus) throughout ontogeny. The surface of the embryo is covered by a two-layered cuticle (commonly called the hyaline layer), which in turn is covered by a granular layer. The granular layer is retained after addition of alcian blue to the fixative solutions, and has not been previously described for any sea urchin. After hatching, the granular layer disappears, but the hyaline layer continues to cover most of the larval surface until settlement and metamorphosis. A few days before metamorphosis, the hyaline layer lining the vestibular invagination of the competent pluteus larva is replaced by a three-layered cuticle resembling that of the adult sea urchin. The hyaline layer covering the rest of the larva is evidently lost at metamorphosis during the involution of the general epidermis.

Key words

Development Sea urchin Hyaline layer Granular layer Ultrastructure 


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Copyright information

© Springer-Verlag 1985

Authors and Affiliations

  • R. Andrew Cameron
    • 1
  • Nicholas D. Holland
    • 2
  1. 1.Department of Marine SciencesUniversity of Puerto RicoMayaguez, Puerto RicoUSA
  2. 2.Marine Biology Research Division, Scripps Institution of OceanographyLa JollaUSA

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