The formation of a hollow lumen in a formerly solid mass of cells is a key developmental process whose dysregulation leads to diseases of the kidney and other organs. Hydrostatic pressure has been proposed to drive lumen expansion, a view that is supported by experiments in the mouse blastocyst. However, lumens formed in other tissues adopt irregular shapes with cell apical faces that are bowed inward, suggesting that pressure may not be the dominant contributor to lumen shape in all cases. Here we use live-cell imaging to study the physical mechanism of lumen formation in Madin-Darby Canine Kidney cell spheroids, a canonical cell-culture model for lumenogenesis. We find that in this system, lumen shape reflects basic geometrical considerations tied to the establishment of apico-basal polarity. A physical model incorporating both cell geometry and intraluminal pressure can account for our observations as well as cases in which pressure plays a dominant role.

在以前的实心细胞团中形成中空管腔是一个关键的发育过程，其失调会导致肾脏和其他器官的疾病。有人提出静水压力可以驱动管腔扩张，这一观点得到了小鼠囊胚实验的支持。然而，在其他组织中形成的管腔采用不规则形状，细胞顶面向内弯曲，这表明压力可能不是在所有情况下管腔形状的主要影响因素。在这里，我们使用活细胞成像来研究 Madin-Darby 犬肾细胞球体中管腔形成的物理机制，这是管腔发生的典型细胞培养模型。我们发现，在该系统中，管腔形状反映了与建立顶端-基底极性相关的基本几何考虑因素。结合细胞几何形状和腔内压力的物理模型可以解释我们的观察以及压力起主导作用的情况。