Cells split in two at the final step of each division cycle. This division normally bisects through the middle of the cell and generates two equal daughters. However, developmental signals can change the plane of cell cleavage to facilitate asymmetric segregation of fate determinants and control the position and relative sizes of daughter cells. The anaphase spindle instructs the site of cell cleavage in animal cells, hence its position is critical in the regulation of symmetric vs asymmetric cell division. Studies in a variety of models identified evolutionarily conserved mechanisms that control spindle positioning. However, how the spindle determines the cleavage site is poorly understood. Recent results in Caenorhabditis elegans indicate dual functions for a Galpha pathway in positioning the spindle and cleavage furrow. We review asymmetric division of the C. elegans zygote, with a focus on microtubule-cortex interactions that position the spindle and cleavage plane.

中文翻译：

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线虫早期胚胎中卵裂平面的测定。

在每个分裂周期的最后一步，细胞分裂成两半。该划分通常在单元的中间一分为二，并生成两个相等的子代。但是，发育信号可以改变细胞分裂的平面，以促进命运决定簇的不对称分离，并控制子代细胞的位置和相对大小。后期纺锤体指示动物细胞中细胞裂解的位置，因此其位置在对称与不对称细胞分裂的调节中至关重要。对各种模型的研究确定了控制主轴定位的进化保守机制。然而，人们对纺锤如何确定卵裂位点了解得很少。秀丽隐杆线虫的最新结果表明，Galpha途径在定位纺锤体和分裂沟中具有双重功能。