Honda Hisao, Nagai Tatsuzo, Tanemura Masaharu
Hyogo University, Kakogawa, Hyogo, Japan.
Dev Dyn. 2008 Jul;237(7):1826-36. doi: 10.1002/dvdy.21609.
During development, certain cells intercalate with each other towards tissue-elongation, exemplified in sea-urchin gut-elongation, amphibian gastrulation, and Drosophila germ-band extension. Their mechanism is not universal among intercalation events. To clarify the minimal cellular properties required for cell-intercalation, we computer-simulated the process using three-dimensional geometrical cell-models. We identified two different mechanisms: (1) cell-junction-remodeling by cell-junction contraction along a specific direction, as observed in Drosophila germ-band extension, and (2) cell-shuffling by orientated cell-extension of bipolar cells, as observed in amphibian gastrulation. The cell-junction-remodeling was characterized by well-defined accumulation of contractile molecules along a specific direction of cell-junctions. Length contraction of approximately one cell-junction per cell is enough for the entire tissue-elongation. The cell-shuffling was characterised by rhythmic cell-extension and orientated movement of cytoskeleton within the elongated cells. Furthermore, tissue-elongation along a polarized axis was limited to a 2.5-fold increase in the cell-junction-remodeling, while no limit was defined for the cell-shuffling.
在发育过程中，某些细胞会相互嵌入以促进组织伸长，海胆肠道伸长、两栖动物原肠胚形成以及果蝇胚带延伸就是例证。它们的机制在嵌入事件中并不通用。为了阐明细胞嵌入所需的最小细胞特性，我们使用三维几何细胞模型对该过程进行了计算机模拟。我们确定了两种不同的机制：（1）细胞连接沿特定方向收缩导致细胞连接重塑，如在果蝇胚带延伸中观察到的那样；（2）双极细胞定向细胞延伸导致细胞重排，如在两栖动物原肠胚形成中观察到的那样。细胞连接重塑的特征是收缩分子沿细胞连接的特定方向有明确的积累。每个细胞大约一个细胞连接的长度收缩就足以实现整个组织的伸长。细胞重排的特征是伸长细胞内细胞的有节奏延伸和细胞骨架的定向运动。此外，沿极化轴的组织伸长在细胞连接重塑中限制为增加2.5倍，而细胞重排则没有限制。
