The precise positioning of organ progenitor cells constitutes an essential, yet poorly understood step during organogenesis. Using primordial germ cells that participate in gonad formation, we present the developmental mechanisms maintaining a motile progenitor cell population at the site where the organ develops. Employing high-resolution live-cell microscopy, we find that repulsive cues coupled with physical barriers confine the cells to the correct bilateral positions. This analysis revealed that cell polarity changes on interaction with the physical barrier and that the establishment of compact clusters involves increased cell-cell interaction time. Using particle-based simulations, we demonstrate the role of reflecting barriers, from which cells turn away on contact, and the importance of proper cell-cell adhesion level for maintaining the tight cell clusters and their correct positioning at the target region. The combination of these developmental and cellular mechanisms prevents organ fusion, controls organ positioning and is thus critical for its proper function.

中文翻译：

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排斥信号与物理屏障和细胞间粘附的结合决定了器官发生过程中祖细胞的定位。

器官祖细胞的精确定位是器官发生过程中必不可少的步骤，但了解甚少。利用参与生殖腺形成的原始生殖细胞，我们提出了在器官发育部位维持运动型祖细胞群体的发育机制。利用高分辨率的活细胞显微镜，我们发现排斥信号与物理屏障相结合，将细胞限制在正确的双边位置。该分析表明，细胞极性随着与物理屏障的相互作用而改变，并且紧密簇的建立涉及增加的细胞-细胞相互作用时间。使用基于粒子的模拟，我们演示了反射屏障的作用，细胞在接触时会从中消失，以及适当的细胞间粘附水平对维持紧密的细胞簇及其在靶区域正确定位的重要性。这些发育和细胞机制的结合阻止了器官融合，控制了器官的位置，因此对其适当的功能至关重要。