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Origin and specification of the neural tube floor plate: insights from the chick and zebrafish
Cells at the ventral midline of the developing neural tube form a specialized structure called the floor plate (FP). FP cells are the source of signaling molecules, including the cell surface and secreted protein Sonic hedgehog (Shh), which - at distinct concentration thresholds - is thought to indu...
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Published in: | Current opinion in neurobiology 2000-02, Vol.10 (1), p.23-30 |
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Main Authors: | , |
Format: | Article |
Language: | English |
Subjects: | |
Online Access: | Get full text |
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Summary: | Cells at the ventral midline of the developing neural tube form a specialized structure called the floor plate (FP). FP cells are the source of signaling molecules, including the cell surface and secreted protein Sonic hedgehog (Shh), which - at distinct concentration thresholds - is thought to induce the interneurons and motoneurons of the spinal cord. Moreover, the FP is responsible for the chemotropic activity that directs the axonal trajectories of commissural interneurons. Recently, the issue of the origin of the FP has become the subject of debate. Experimentation, largely on the chick embryo, led to the widely accepted model that the FP is formed through an induction from the notochord to the overlying neural plate. The induction is mediated by notochord-derived Shh and requires direct cellular contact. In this model, future FP cells are initially equivalent to the other cells of the neurectoderm, as far as their origin and developmental potential are concerned. The model of Shh-mediated induction of FP (and motoneurons) by the notochord, while attractive in its simplicity, has been challenged in certain, but not all, of its aspects through analyses of quail-chick chimeras and zebrafish mutants. |
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ISSN: | 0959-4388 |
DOI: | 10.1016/S0959-4388(99)00062-8 |