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Article: Modified spiral cleavage: the duet cleavage pattern and early blastomere fates in the acoel turbellarian Neochildia fusca.
- Article from:
- The Biological Bulletin
- Article date:
- October 1, 1996
- Author:
CopyrightCOPYRIGHT 1996 Marine Biological Laboratory. This material is published under license from the publisher through the Gale Group, Farmington Hills, Michigan. All inquiries regarding rights should be directed to the Gale Group. (Hide copyright information)
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Spiral cleavage, which characterizes the embryos of phyla belonging to the Spiralia, typically involves the generation of four quartets of micromeres from the four macromeres produced by the first and second cleavages. The direction of the cleavage planes forming the micromere quartets alternates between dexiotropic (clockwise) and laeotropic (counterclockwise), with the first quartet usually resulting from a dexiotropic division to the eight-cell stage. Cell lineage studies of embryos with quartet spiral cleavage demonstrate that the first three quartets form ectoderm (1).
Embryos of the acoel turbellarian Platyhelminthes exhibit a modified form of spiral ...