Green Center for Systems Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9050
Department of Chemical and Biomolecular Engineering, University of California, Berkeley, CA 94720, USA.
Development. 2018 Dec 10;145(24):dev167387. doi: 10.1242/dev.167387.
Understanding how forces and material properties give rise to tissue shapes is a fundamental issue in developmental biology. Although gastrulation is a well-used system for investigating tissue morphogenesis, a consensus mechanical model that explains all the key features of this process does not exist. One key feature of gastrulation is its anisotropy: the mesoderm constricts much more along one axis than along the other. Previous explanations have involved graded stress, anisotropic stresses or material properties, or mechanosensitive feedback. Here, we show that these mechanisms are not required to explain the anisotropy of constriction. Instead, constriction can be anisotropic if only two conditions are met: the tissue is elastic, as was demonstrated in our recent study; and the contractile domain is asymmetric. This conclusion is general and does not depend on the values of model parameters. Our model can explain results from classical tissue-grafting experiments and from more-recent laser ablation studies. Furthermore, our model may provide alternative explanations for experiments in other developmental systems, including and zebrafish.
理解力和物质属性如何导致组织形状的形成是发育生物学中的一个基本问题。尽管原肠胚形成是一个用于研究组织形态发生的常用系统，但不存在一个能够解释这个过程所有关键特征的共识力学模型。原肠胚形成的一个关键特征是各向异性：中胚层在一个轴上的收缩程度远远大于另一个轴上的收缩程度。先前的解释涉及梯度应力、各向异性应力或材料属性，或机械敏感性反馈。在这里，我们表明，这些机制并不需要解释收缩的各向异性。相反，如果满足以下两个条件，收缩就可以是各向异性的：组织是有弹性的，正如我们最近的研究所示；并且收缩域是不对称的。这个结论是普遍的，不依赖于模型参数的值。我们的模型可以解释经典的组织移植实验和最近的激光消融研究的结果。此外，我们的模型可能为其他发育系统的实验提供替代解释，包括果蝇和斑马鱼。
