Komatsu Valerie, Doddihal Viraj, Chang Chenbei
University of Southern California, Los Angeles, CA 90089.
Embryology: Concepts & Techniques in Modern Developmental Biology, Marine Biological Laboratory, Woods Hole, MA, 02543.
MicroPubl Biol. 2021 Oct 14;2021. doi: 10.17912/micropub.biology.000483. eCollection 2021.
Gastrulation involves coordinated movements of cells, facilitating mesoderm and endoderm internalization and proper patterning of tissues across the germ layers. In , head mesoderm migrates collectively along the blastocoel roof fibronectin network towards the animal pole. Meanwhile, the trunk mesodermal cells migrate over each other in convergent thickening and convergent extension movements elongating the body axis. The behaviors of cells in these regions are investigated mainly in tissue explants taken from the respective head or trunk mesodermal regions. How cells behave at the transitional zone between these territories is not described in detail. To learn about cell behaviors around this junction, we imaged cell movements in an explant that encompassed the head and trunk mesoderm. We observed that head mesoderm migration on fibronectin employed lamellipodial protrusions at the leading edge and dynamic actin remodeling in the trailing cells. Trunk mesodermal cells underwent mediolateral cell elongation and intercalation to form the notochord. Lateral edges of the notochord were defined before the anterior edge. Our movie reveals distinct mesodermal cell behaviors occurring simultaneously in different regions of gastrulating embryos. This study highlights the power of applying modern microscopy tools to revisit classical experiments, permitting a greater understanding of the cellular dynamics that shape the embryo.
原肠胚形成涉及细胞的协调运动，促进中胚层和内胚层的内化以及跨胚层组织的正确模式形成。在[具体情况未提及]中，头部中胚层沿着囊胚腔顶的纤连蛋白网络集体迁移至动物极。与此同时，躯干中胚层细胞在汇聚增厚和汇聚延伸运动中相互迁移，从而拉长身体轴。这些区域细胞的行为主要在取自各自头部或躯干中胚层区域的组织外植体中进行研究。细胞在这些区域之间的过渡区如何表现并未详细描述。为了解该交界处周围的细胞行为，我们对包含头部和躯干中胚层的外植体中的细胞运动进行了成像。我们观察到，头部中胚层在纤连蛋白上的迁移在前缘采用片状伪足突起，在后随细胞中进行动态肌动蛋白重塑。躯干中胚层细胞经历了中外侧细胞伸长和插入以形成脊索。脊索的外侧边缘在其前缘之前就已确定。我们的影片揭示了原肠胚形成胚胎不同区域同时发生的独特中胚层细胞行为。这项研究突出了应用现代显微镜工具重新审视经典实验的作用，有助于更深入地理解塑造胚胎的细胞动力学。
