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Psychoyos D, Stern CD. Restoration of the organizer after radical ablation of Hensen's node and the anterior primitive streak in the chick embryo. Development 1996; 122:3263-73. [PMID: 8898238 DOI: 10.1242/dev.122.10.3263] [Citation(s) in RCA: 81] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The region of the amniote embryo corresponding to Spemann's organizer in amphibians is Hensen's node, which lies at the tip of the primitive streak during gastrulation. It is a special site in the embryo that can be defined by the presence of progenitors of several axial tissues (notochord, prechordal mesoderm, somites, gut endoderm), by characteristic cell movements, by specific patterns of gene expression (e.g. goosecoid, HNF-3beta, Sonic hedgehog) and, most importantly, by its ability to induce a complete axis, including host-derived neural tissue, when transplanted to an ectopic site. Here, we show that complete removal not only of the node but also of the anterior 40% of the primitive streak leads to the development of normal embryos containing cells with all the fates normally produced by the node. Cell movement pathways through the regenerated node are identical to those seen in the normal embryo. The patterns of expression of HNF-3beta and Sonic hedgehog are also restored, as is their left/right asymmetry, but goosecoid expression is not. When the regenerated node is transplanted to an ectopic site, it induces a complete embryonic axis that includes a fully patterned, host-derived central nervous system. Analysis of the properties of cells surrounding the site of ablation shows that they acquire these properties gradually. We suggest that the organizer is a region of the embryo that is defined by cell interactions and that the node normally inhibits the organizer state in neighbouring cells.
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Affiliation(s)
- D Psychoyos
- Department of Genetics and Development, College of Physicians and Surgeons of Columbia University, New York, NY 10032, USA
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Wourms JP. The developmental biology of annual fishes. II. Naturally occurring dispersion and reaggregation of blastomers during the development of annual fish eggs. THE JOURNAL OF EXPERIMENTAL ZOOLOGY 1972; 182:169-200. [PMID: 5079084 DOI: 10.1002/jez.1401820203] [Citation(s) in RCA: 128] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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Brummett AR. Deletion-transplantation experiments on embryos of Fundulus heteroclitus. II. The anterior embryonic shield. THE JOURNAL OF EXPERIMENTAL ZOOLOGY 1969; 172:443-63. [PMID: 5392882 DOI: 10.1002/jez.1401720408] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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