Anisotropic growth shapes intestinal tissues during embryogenesis
Anisotropic growth shapes intestinal tissues during embryogenesis
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DOI：
10.1073/pnas.1217391110
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发表时间：
2013-06-25
影响因子：
11.1
通讯作者：
Jia, Fei
中科院分区：
文献类型：
--
作者：
Ben Amar, Martine;Jia, Fei
胚胎发生为软组织生长诱导的模式形成、屈曲和后屈曲提供了一个真正的实验室。我们身体的每一部分都是由多个相邻的层构成的：皮肤、大脑和器官内部。每一层都有复杂的生物组成，呈现出不同的弹性。这些层是在胎儿时期形成的，在受精后的早期阶段会经历生长和重塑。在这里，我们关注胎儿肠道组织中出现的人字形模式。对于许多哺乳动物来说，这种不稳定性是绒毛（指状突起）进入管腔的前兆。对于禽类（小鸡和火鸡的胚胎），研究表明，受精后几天，十二指肠粘膜上皮是光滑的，然后出现褶皱，在2天后呈现明显的锯齿状不稳定性。许多争论和生物学研究都致力于这种特定的形态，它调节了肠道中的细胞更新。在回顾有关十二指肠形态发生的实验结果的基础上，我们提出了一个基于简化假设的间质生长模型可以解释十二指肠屈曲和后屈曲不稳定性。它是完全解析的，基于层间生长差异引起的双轴压应力，并定量预测了形态变化。生长各向异性随时间的增加，褶皱和之字形之间的竞争，被证明是次要的不稳定性。该模型可与已有的鸡十二指肠实验数据进行比较，并可应用于其他肠道组织，这种“之字形”是肠胚发生过程中常见而壮观的微观结构模式。
Embryogenesis offers a real laboratory for pattern formation, buckling, and postbuckling induced by growth of soft tissues. Each part of our body is structured in multiple adjacent layers: the skin, the brain, and the interior of organs. Each layer has a complex biological composition presenting different elasticity. Generated during fetal life, these layers will experience growth and remodeling in the early postfertilization stages. Here, we focus on a herringbone pattern occurring in fetal intestinal tissues. Common to many mammalians, this instability is a precursor of the villi, finger-like projections into the lumen. For avians (chicks' and turkeys' embryos), it has been shown that, a few days after fertilization, the mucosal epithelium of the duodenum is smooth, and then folds emerge, which present 2 d later a pronounced zigzag instability. Many debates and biological studies are devoted to this specific morphology, which regulates the cell renewal in the intestine. After reviewing experimental results about duodenum morphogenesis, we show that a model based on simplified hypothesis for the growth of the mesenchyme can explain buckling and postbuckling instabilities. Being completely analytical, it is based on biaxial compressive stresses due to differential growth between layers and it predicts quantitatively the morphological changes. The growth anisotropy increasing with time, the competition between folds and zigzags, is proved to occur as a secondary instability. The model is compared with available experimental data on chick's duodenum and can be applied to other intestinal tissues, the zigzag being a common and spectacular microstructural pattern of intestine embryogenesis.