The Spawning and Early Development of the Hawaiian Acorn Worm (Hemichordate), Ptychodera flava

Zoological Science
K TagawaN Satoh

Abstract

The spawning and early embryogenesis of the hemichordate, Ptychodera flava, in Hawaii are described in detail and illustrated with photographs of living material. Natural spawning in the evenings of early December was induced by a shift of seawater temperature from about 22 degrees C to about 26 degrees C. The fertilized egg divides equally and slowly at first, reaching 8 cells at about 5 hr after insemination at room temperature (20-24 degrees C). Divisions then appear to become slightly unequal and by 9 hr the embryo has divided into about 100 cells. The blastocoel forms during cleavage as an irregular space that, when viewed from the side, tends to appear oblate and ultimately appear crescent-shaped as the vegetal plate thickens into the blastocoel. The archenteron forms at about 18 hr as a cleft beginning at the vegetal pole and extending into the vegetal plate. As development proceeds, the embryo expands and by 24 hr forms a typical deuterostome gastrula with an outer sphere of ectoderm and a inner tube of endoderm connected at the blastopore. An out-pocketing of the gut appears at the tip of the archenteron over the next 4 hr to form the protocoel which will become the proboscis coelom. Approaching 40 hr the gut becomes a...Continue Reading

References

Jul 1, 1988·Roux's Archives of Developmental Biology : the Official Organ of the EDBO·Gary Freeman, Ellis B Ridgway

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Citations

Sep 18, 1998·Mechanisms of Development·K TagawaN Satoh
Jun 8, 2014·Integrative and Comparative Biology·Antje H L FischerJoel Smith
Dec 15, 2015·Journal of Experimental Zoology. Part B, Molecular and Developmental Evolution·Ching-Yi LinYi-Hsien Su
Mar 8, 2000·Mechanisms of Development·Y HaradaN Satoh
Jan 25, 2002·Evolution & Development·J Q HenryM Q Martindale
May 1, 2007·Journal of Morphology·Claus Nielsen, Anders Hay-Schmidt
May 9, 2012·Zoological Science·Makoto UrataSusumu Ohtsuka
Apr 11, 2020·Development, Growth & Differentiation·Yuuri Yasuoka
Feb 10, 2010·Zoological Science·Tom HumphreysKuni Tagawa
Jun 28, 2012·Development·Eric Röttinger, Christopher J Lowe

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