Patten Iain, Kulesa Paul, Shen Michael M, Fraser Scott, Placzek Marysia
Centre for Developmental Genetics, Department of Biomedical Science, University of Sheffield, Sheffield S10 2TN, UK.
Development. 2003 Oct;130(20):4809-21. doi: 10.1242/dev.00694. Epub 2003 Aug 13.
To begin to reconcile models of floor plate formation in the vertebrate neural tube, we have performed experiments aimed at understanding the development of the early floor plate in the chick embryo. Using real-time analyses of cell behaviour, we provide evidence that the principal contributor to the early neural midline, the future anterior floor plate, exists as a separate population of floor plate precursor cells in the epiblast of the gastrula stage embryo, and does not share a lineage with axial mesoderm. Analysis of the tissue interactions associated with differentiation of these cells to a floor plate fate reveals a role for the nascent prechordal mesoderm, indicating that more than one inductive event is associated with floor plate formation along the length of the neuraxis. We show that Nr1, a chick nodal homologue, is expressed in the nascent prechordal mesoderm and we provide evidence that Nodal signalling can cooperate with Shh to induce the epiblast precursors to a floor-plate fate. These results indicate that a shared lineage with axial mesoderm cells is not a pre-requisite for floor plate differentiation and suggest parallels between the development of the floor plate in amniote and anamniote embryos.
为了开始协调脊椎动物神经管底板形成的模型，我们进行了旨在了解鸡胚早期底板发育的实验。通过对细胞行为的实时分析，我们提供了证据表明，早期神经中线（未来的前底板）的主要贡献者，在原肠胚阶段胚胎的外胚层中作为底板前体细胞的一个独立群体存在，并且与轴中胚层没有共同的谱系。对与这些细胞分化为底板命运相关的组织相互作用的分析揭示了新生前索中胚层的作用，表明沿着神经轴的长度，不止一个诱导事件与底板形成相关。我们表明，鸡的Nodal同源物Nr1在新生前索中胚层中表达，并且我们提供了证据表明Nodal信号可以与Shh协同作用，诱导外胚层前体分化为底板命运。这些结果表明，与轴中胚层细胞有共同的谱系不是底板分化的先决条件，并提示了羊膜动物和无羊膜动物胚胎底板发育之间的相似之处。
