PDF(Pubmed)
Abstract：
In the early avian embryo, the developing heart forms when bilateral fields of cardiac progenitor cells, which reside in the lateral plate mesoderm, move toward the embryonic midline, and fuse above the anterior intestinal portal (AIP) to form a straight, muscle-wrapped tube. During this process, the precardiac mesoderm remains in close contact with the underlying endoderm. Previous work has shown that the endoderm around the AIP actively contracts to pull the cardiac progenitors toward the midline. The morphogenetic deformations associated with this endodermal convergence, however, remain unclear, as do the signaling pathways that might regulate this process. Here, we fluorescently labeled populations of endodermal cells in early chicken embryos and tracked their motion during heart tube formation to compute time-varying strains along the anterior endoderm. We then determined how the computed endodermal strain distributions are affected by the pharmacological inhibition of either myosin II or fibroblast growth factor (FGF) signaling. Our data indicate that a mediolateral gradient in endodermal shortening is present around the AIP, as well as substantial convergence and extension movements both anterior and lateral to the AIP. These active endodermal deformations are disrupted if either actomyosin contractility or FGF signaling are inhibited pharmacologically. Taken together, these results demonstrate how active deformations along the anterior endoderm contribute to heart tube formation within the developing embryo.
摘要：
在早期的鸟类胚胎中，当心脏祖细胞的双侧视野时，发育中的心脏形成，位于外侧板中胚层，向胚胎中线移动，并在前肠门（AIP）上方融合形成一条直线，肌肉包裹的管子.在这个过程中,心前中胚层与下面的内胚层保持紧密接触。先前的工作表明，AIP周围的内胚层主动收缩，将心脏祖细胞拉向中线。与这种内胚层收敛相关的形态发生变形，然而,仍不清楚,可能调节这一过程的信号通路也是如此。这里,我们对早期鸡胚中的内胚层细胞群进行荧光标记，并跟踪其在心管形成过程中的运动，以计算沿着前内胚层的随时间变化的菌株。然后，我们确定计算的内胚层菌株分布如何受到肌球蛋白II或成纤维细胞生长因子（FGF）信号传导的药理学抑制的影响。我们的数据表明，AIP周围存在内胚层缩短的中外侧梯度，以及AIP前后的大量收敛和延伸运动。如果在药理学上抑制肌动球蛋白收缩性或FGF信号传导，则这些活性内胚层变形被破坏。一起来看,这些结果证明了沿着前内胚层的主动变形如何有助于发育中的胚胎内的心脏管形成。
