Collective motions of epithelial cells in vivo are essential for morphogenesis in developmental biology. Tissues elongate, contract, flow, and oscillate, thus sculpting embryos. These tissue level dynamics are known, but the physical mechanisms at the cellular level are unclear, with various behaviors depending on the tissues and species. Moreover, investigations on in vitro tissue behavior usually focus on only one type of cell dynamics and use diverse theoretical approaches, making systematic comparisons between studies challenging. Here, we show that a single epithelial monolayer of Madin Darby Canine Kidney (MDCK) cells can exhibit two types of local tissue kinematics, pulsations and long range coherent flows. We analyzed these distinct motions by using quantitative live imaging. We also report that these motions can be controlled with internal and external cues such as specific inhibitors, and friction modulation of the substrate by microcontact printing method. We further demonstrate with a unified vertex model that both behaviors depend on the competition between velocity alignment and random diffusion of cell polarization. When alignment and diffusion are comparable, a pulsatile flow emerges, whereas the tissue undergoes long-range flows when velocity alignment dominates. We propose that environmental friction, acto-myosin distributions, and cell polarization kinetics are important in regulating the dynamics of tissue morphogenesis.

中文翻译：

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组织中的脉动和流动：具有简单细胞规则的两种集体动力学

体内上皮细胞的集体运动对于发育生物学中的形态发生至关重要。组织伸长、收缩、流动和振荡，从而塑造胚胎。这些组织水平的动力学是已知的，但细胞水平的物理机制尚不清楚，其行为取决于组织和物种。此外，体外研究组织行为通常只关注一种类型的细胞动力学并使用不同的理论方法，这使得研究之间的系统比较具有挑战性。在这里，我们展示了 Madin Darby 犬肾 (MDCK) 细胞的单个上皮单层可以表现出两种类型的局部组织运动学、脉动和长程相干流。我们通过使用定量实时成像分析了这些不同的运动。我们还报告说，这些运动可以通过内部和外部线索来控制，例如特定的抑制剂，以及通过微接触印刷方法对基板的摩擦调制。我们通过统一的顶点模型进一步证明，这两种行为都取决于速度对齐和细胞极化的随机扩散之间的竞争。当排列和扩散相当时，就会出现脉动流，而当速度对齐占主导地位时，组织会经历长程流动。我们提出环境摩擦、肌动球蛋白分布和细胞极化动力学对于调节组织形态发生的动力学很重要。