Luchinskaia N N, Belousov L V, Shteĭn A A
Ontogenez. 1997 Mar-Apr;28(2):106-16.
The ventral ectoderm explants of the Xenopus laevis early gastrula were stretched on an elastic substrate 1.5- to twofold for 30 min, then fixed in the stretched state and incubated for up to 6 h. The stretching of explants generated their two-phase active reaction, which was estimated using the criterion of eccentricity of cells and whole explants developed in this study. At the first phase, during the external force application, the explant cells were elongated towards its stretching to a markedly greater extent than the whole explant: eccentricity of the whole cells exceeded that of the whole explants. Cell processes elongated in the same direction appeared, cell contacts and apical cytoskeleton structures developed, and mechanical tensions increased. At the second phase, within 5 h after the stretching, the shape of individual cells, rather than the whole explant, returned to the initial one (approximately isotropic), mechanical tensions decreased, and visible morphogenesis of the explant proceeded: it acquired a complex shape with longitudinal groove and polar thickenings. We conclude that intercalary movements of the cells are present at the second phase of the active explant reaction and morphogenesis is realized at the phase of relaxation of mechanical tensions.
将非洲爪蟾早期原肠胚的腹侧外胚层外植体在弹性基质上拉伸1.5至两倍，持续30分钟，然后在拉伸状态下固定，并孵育长达6小时。外植体的拉伸产生了其两阶段的活性反应，该反应使用本研究中发育的细胞和整个外植体的偏心率标准进行评估。在第一阶段，在外力施加期间，外植体细胞向其拉伸方向伸长的程度明显大于整个外植体：整个细胞的偏心率超过整个外植体的偏心率。出现了沿相同方向伸长的细胞突起，细胞接触和顶端细胞骨架结构发育，机械张力增加。在第二阶段，在拉伸后5小时内，单个细胞而非整个外植体的形状恢复到初始状态（近似各向同性），机械张力降低，外植体开始明显的形态发生：它获得了带有纵向凹槽和极性增厚的复杂形状。我们得出结论，细胞的插入运动存在于活性外植体反应的第二阶段，形态发生在机械张力松弛阶段实现。
