Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520, USA.
Development. 2013 Feb 1;140(3):573-82. doi: 10.1242/dev.090381.
The tailbud is the posterior leading edge of the growing vertebrate embryo and consists of motile progenitors of the axial skeleton, musculature and spinal cord. We measure the 3D cell flow field of the zebrafish tailbud and identify changes in tissue fluidity revealed by reductions in the coherence of cell motion without alteration of cell velocities. We find a directed posterior flow wherein the polarization between individual cell motion is high, reflecting ordered collective migration. At the posterior tip of the tailbud, this flow makes sharp bilateral turns facilitated by extensive cell mixing due to increased directional variability of individual cell motions. Inhibition of Wnt or Fgf signaling or cadherin 2 function reduces the coherence of the flow but has different consequences for trunk and tail extension. Modeling and additional data analyses suggest that the balance between the coherence and rate of cell flow determines whether body elongation is linear or whether congestion forms within the flow and the body axis becomes contorted.
尾芽是生长中脊椎动物胚胎的后端前缘，包含轴向骨骼、肌肉和脊髓的游动祖细胞。我们测量了斑马鱼尾芽的三维细胞流动场，并识别出组织流动性的变化，这种变化是通过降低细胞运动的相干性而不改变细胞速度来揭示的。我们发现了一种定向的向后流动，其中个体细胞运动之间的极化程度很高，反映了有序的集体迁移。在尾芽的后端，由于个体细胞运动的方向变化增加，导致细胞混合广泛，这种流动使得双边急剧转弯成为可能。抑制 Wnt 或 Fgf 信号或钙黏蛋白 2 功能会降低流动的相干性，但对躯干和尾部的延伸有不同的影响。建模和额外的数据分析表明，细胞流动的相干性和速率之间的平衡决定了身体的伸长是线性的，还是在流动中发生拥堵，使身体轴变得扭曲。
