LOCAL SHIFTS IN POSITION AND POLARIZED MOTILITY DRIVE CELL REARRANGEMENT DURING SEA-URCHIN GASTRULATION
LOCAL SHIFTS IN POSITION AND POLARIZED MOTILITY DRIVE CELL REARRANGEMENT DURING SEA-URCHIN GASTRULATION
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DOI：
10.1016/0012-1606(89)90268-6
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发表时间：
1989-12-01
影响因子：
2.7
通讯作者：
HARDIN, J
中科院分区：
文献类型：
--
作者：
HARDIN, J
本研究探讨上皮细胞重排的机制，在原肠延长海胆胚胎，使用扫描电子显微镜，微分干涉对比视频显微镜，细胞标记，荧光标记嵌合克隆。原肠的伸长包括两个主要过程：原肠壁细胞位置的局部变化和细胞重新排列时的极化运动。引入红腹长尾鳕原肠的标记嵌合体克隆最初为4-5个细胞宽;到原肠胚形成结束时，克隆伸长并变窄，使得它们在原肠的最西部区域为一个细胞宽。克隆混合的程度表明，在细胞重排过程中，原肠中的细胞仅改变1-2个细胞直径的相对位置。囊胚孔的细胞与原肠中的细胞同时重排，导致囊胚孔直径减小35%。当内胚层细胞重排时，它们在形状和运动性上经历极化的、阶段特异性的变化：（1）在整个原肠延长过程中，它们沿其顶基轴沿着显著变平;（2）就在细胞重排开始之前，原肠中所有细胞的基表面沿原肠延伸轴沿着延伸长的极化板状突起;（3）随着细胞重排的开始，细胞基表面逐渐变圆，细胞变得等径;（4）到3/4 gatrula阶段，细胞沿动物-植物轴沿着伸展，显然是由于丝状伪足牵引，最后（5）它们继续重新排列，在原肠胚形成结束时恢复到不那么细长的形状。在cidaroid Eucidaris tribuloides原肠胚形成的直接观察表明，在这个物种中，细胞重排是通过细胞无向上的丝状伪足的渐进式圆周嵌入完成的。这种插入伴随着细胞边界处的爆炸性的、明显随机的皮质起泡活动，这表明除了丝状伪足张力可能产生的任何细胞修复外，这种活动是主动修复过程的重要组成部分。
This study examines the mechanism of epithelial cell rearrangement during archenteron elongation in the sea urchin embryo using scanning electron microscopy, differential interference contrast videomicroscopy, cell marking, and fluorescently labeled chimaeric clones. Archenteron elongation involves two major processes: local shifts in position of cells in the archenteron wall and polarized motility of the cells as they rearrange. Fluorescently labeled chimaeric clones introduced into the archenteron of Lytechinus pictus are initially 4-5 cells wide; by the end of gastrulation the clones elongate and narrow, so that they are one cell wide in the narrowest region of the archenteron. The extent of clonal mixing indicates that cells in the archenteron change their relative positions by only 1-2 cell diameters during cell rearrangement. Cells at the blastopore rearrange concomitantly with cells in the archenteron, resulting in a 35% decrease in blastopore diameter. Endoderm cells undergo polarized, stage-specific changes in shape and motility as they rearrange: (1) they flatten markedly along their apical-basal axis throughout archenteron elongation; (2) just prior to the onset of cell rearrangement, basal surfaces of all cells in the archenteron extend long, polarized lamellipodial protrusions along the axis of extension of the archenteron; (3) as cell rearrangement begins, basal surfaces round up and the cells become isodiametric; (4) by the 3/4 gatrula stage the cells become stretched along the animal-vegetal axis, apparently due to filopodial traction, and finally (5) they continue to rearrange, returning to a less elongated shape by the end of gastrulation. Direct observation of gastrulation in the cidaroid Eucidaris tribuloides indicates that in this species cell rearrangement is accomplished by progressive circumferential intercalation of cells without upwardly directed filopodia. This intercalation is accompanied by explosive, apparently stochastic, cortical blebbing activity at the boundaries between cells, suggesting that in addition to whatever cell rearrangment may be generated by filopodial tension, such activity is an important component of the active rearrangment process.