Document Detail

The development of the enteropneust hemichordate Balanoglossus misakiensis KUWANO.
MedLine Citation:
PMID:  15170057     Owner:  NLM     Status:  MEDLINE    
We describe development from fertilization to metamorphosis of the enteropneust hemichordate Balanoglossus misakiensis. This is the first report to describe the complete development of an indirect-developing hemichordate under laboratory conditions. Mature adults were induced to spawn by shifting the temperature of seawater from 23 to 28 degrees C. Eggs (200 microm diameter) were enclosed within a non-mucilaginous membrane, and dispersed readily in seawater. After artificial insemination, a fertilization envelope was elevated from the egg surface beneath the egg membrane; this was followed by the formation of the first and second polar bodies within the envelope. Zygotes cleaved at 20-min intervals to form blastulae, and gastrulation started 9 h after fertilization. Embryos hatched 1 day after fertilization to become typical feeding tornaria larvae. The larvae metamorphosed 7-10 days after fertilization without undergoing the first (Müller) or forth (Krohn) stage of indirect-developing hemichordate development. Larvae that were not fed failed to metamorphose. Juveniles completed adult body formation within a week of settling in sand at the bottom of the culture tube. We discuss heterochronical modifications of B. misakiensis development, and make the case for this species as a potential model organism for the investigation of indirect-developing hemichordates.
Makoto Urata; Masaaki Yamaguchi
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Zoological science     Volume:  21     ISSN:  0289-0003     ISO Abbreviation:  Zool. Sci.     Publication Date:  2004 May 
Date Detail:
Created Date:  2004-05-31     Completed Date:  2004-08-04     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  8702287     Medline TA:  Zoolog Sci     Country:  Japan    
Other Details:
Languages:  eng     Pagination:  533-40     Citation Subset:  IM    
Division of Life Science, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Japan.
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MeSH Terms
Cleavage Stage, Ovum / physiology*
Invertebrates / embryology*,  physiology
Larva / growth & development
Metamorphosis, Biological / physiology*
Ovum / cytology*
Time Factors

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