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International Journal of Zoology
Volume 2010, Article ID 572502, 10 pages
Research Article

Mosaic and Regulation Phenomena during the Early Formation of the Chick Blastoderm

Laboratory of Human Anatomy and Embryology, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerpen, Belgium

Received 9 July 2009; Revised 21 October 2009; Accepted 11 January 2010

Academic Editor: Greg Demas

Copyright © 2010 Marc Callebaut et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


After culturing symmetrically hemisectioned unincubated chicken blastoderms, asymmetric hemiembryos developed (indicating mosaic development). In the present study, we observed that after prolonged culture, the further asymmetric development (way with no possible return) becomes profoundly disturbed, more particularly the Rauber's sickle-dependent phenomena: gastrulation and the formation of the coelomo-cardiovascular complex with absence of heart and pericard development. By contrast, the neural plate develops symmetrically. Asymmetrical ablation of Rauber's sickle and the neighboring upper layer results in the development of an apparently normal symmetrical embryo. Indeed, at the unoperated side, a normal half coelomo-cardiovascular system develops with a unilateral or bilateral heart tube and pericard formation (indicating regulation). Both regulation and mosaicism indicate that during normal early development, the interaction between the left and right sides of the caudal area centralis of the blastoderm is indispensable, depending on the spatial relationship between the elementary tissues (upper layer, Rauber's sickle, endophyll).