Development of a "Primitive" Sea Urchin (Eucidaris tribuloides): Irregularities in the Hyaline Layer, Micromeres, and Primary Mesenchyme

The normal embryonic development of the cidaroid sea urchin Eucidaris tribuloides from fertilization to the late two-armed larval stage is described with the aid of light and electron microscopy. Unusual developmental features include a virtual absence of a hyaline layer, irregularities in the numbe...

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Bibliographic Details
Published in:The Biological bulletin (Lancaster) 1981-08, Vol.161 (1), p.141-151
Main Author: Schroeder, Thomas E.
Format: Article
Language:English
Subjects:
Blastomeres
Cell lines
Developmental biology
Embryos
Eucidaris tribuloides
Fertilization
Hyalin
Larvae
Larval development
Marine
Sea urchins
Skeleton
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Description
Summary:The normal embryonic development of the cidaroid sea urchin Eucidaris tribuloides from fertilization to the late two-armed larval stage is described with the aid of light and electron microscopy. Unusual developmental features include a virtual absence of a hyaline layer, irregularities in the number and size of micromeres, and a total lack of early mesenchyme (the so-called primary mesenchyme). These and other features are unlike developmental characters in the euechinoids ("modern" sea urchins). They are discussed with reference to the phylogeny of sea urchins. Eucidaris tribuloides may exhibit "primitive" developmental patterns representative of the cidaroid ancestor which was common to all living sea urchins.
ISSN:0006-3185
1939-8697
DOI:10.2307/1541114