Oocytes are large cells that develop into an embryo upon fertilization¹. As interconnected germ cells mature into oocytes, some of them grow—typically at the expense of others that undergo cell death^2,3,4. We present evidence that in the nematode Caenorhabditis elegans, this cell-fate decision is mechanical and related to tissue hydraulics. An analysis of germ cell volumes and material fluxes identifies a hydraulic instability that amplifies volume differences and causes some germ cells to grow and others to shrink, a phenomenon that is related to the two-balloon instability⁵. Shrinking germ cells are extruded and they die, as we demonstrate by artificially reducing germ cell volumes via thermoviscous pumping⁶. Our work reveals a hydraulic symmetry-breaking transition central to the decision between life and death in the nematode germline.

卵母细胞是受精后发育成胚胎的大细胞¹ 。当相互连接的生殖细胞成熟为卵母细胞时，其中一些会生长，通常是以其他经历细胞死亡为代价的^2,3,4 。我们提出的证据表明，在线虫秀丽隐杆线虫中，这种细胞命运决定是机械性的，并且与组织水力学有关。对生殖细胞体积和物质通量的分析发现了水力不稳定性，这种不稳定性会放大体积差异并导致一些生殖细胞生长而另一些生殖细胞收缩，这种现象与双球囊不稳定性有关⁵ 。正如我们通过热粘性泵人工减少生殖细胞体积所证明的那样，收缩的生殖细胞被挤出并死亡⁶ 。我们的工作揭示了水力对称性破坏的转变对于线虫种系的生死决定至关重要。