Mesodermal cell displacements during avian gastrulation are due to both individual cell-autonomous and convective tissue movements
Mesodermal cell displacements during avian gastrulation are due to both individual cell-autonomous and convective tissue movements
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DOI：
10.1073/pnas.0606100103
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发表时间：
2006-12-26
影响因子：
11.1
通讯作者：
Rongish, Brenda J.
中科院分区：
文献类型：
--
作者：
Zamir, Evan A.;Czirok, Andras;Rongish, Brenda J.
原肠胚形成是早期发育的基本过程，导致三个初级胚层的形成。在鸟类原肠胚形成过程中，背侧上胚层中的假定中胚层细胞通过称为原始条纹（PS）的沟槽进入，随后离开PS并形成成体组织。生物物理机制驱动中胚层细胞运动在原肠胚，特别是温血胚胎，还不清楚。到目前为止，一个主要的挑战一直是区分局部个体细胞自主（主动）位移对流位移所造成的大规模（散装）形态发生组织运动。为了解决这个问题，我们使用多尺度，延时显微镜和粒子图像测速方法计算组织位移场。免疫标记的纤连蛋白被用作定量组织位移的原位标记物。通过同时对荧光标记的中胚层细胞和周围的细胞外基质进行成像，我们能够直接分离原肠胚形成期间细胞位移的主动和被动成分。我们的研究结果揭示了以下几点：（t）对流组织运动对总细胞位移有显著的贡献，必须减去以测量真正的细胞自主位移;（it）细胞自主位移在从PS流出后逐渐减少;（iii）有一个增加的头到尾（头到尾）细胞自主运动梯度，尾细胞主动远离PS的速度比颅细胞快。这些研究表明，在胚胎的某些区域，总中胚层细胞位移主要是由于对流组织运动;因此，这些数据对于理解温血胚胎中的细胞引导机制和组织形态发生具有深远的意义。
Gastrulation is a fundamental process in early development that results in the formation of three primary germ layers. During avian gastrulation, presumptive mesodermal cells in the dorsal epiblast ingress through a furrow called the primitive streak (PS), and subsequently move away from the PS and form adult tissues. The biophysical mechanisms driving mesodermal cell movements during gastrulation in amniotes, notably warm-blooded embryos, are not understood. Until now, a major challenge has been distinguishing local individual cell-autonomous (active) displacements from convective displacements caused by large-scale (bulk) morphogenetic tissue movements. To address this problem, we used multiscale, time-lapse microscopy and a particle image velocimetry method for computing tissue displacement fields. Immunolabeled fibronectin was used as an in situ marker for quantifying tissue displacements. By imaging fluorescently labeled mesodermal cells and surrounding extracellular matrix simultaneously, we were able to separate directly the active and passive components of cell displacement during gastrulation. Our results reveal the following: (t) Convective tissue motion contributes significantly to total cell displacement and must be subtracted to measure true cell-autonomous displacement; (it) Cell-autonomous displacement decreases gradually after egression from the PS; and (iii) There is an increasing cranial-to-caudal (head-to-tail) cell-autonomous motility gradient, with caudal cells actively moving away from the PS faster than cranial cells. These studies show that, in some regions of the embryo, total mesodermal cell displacements are mostly due to convective tissue movements; thus, the data have profound implications for understanding cell guidance mechanisms and tissue morphogenesis in warm-blooded embryos.