Physics Faculty, Southern Federal University, 344090 Rostov-on-Don, Russia.
Lillehei Heart Institute, Department of Medicine, University of Minnesota, Minneapolis, Minnesota, MN 55455, USA.
Phys Rev E. 2023 Aug;108(2-1):024404. doi: 10.1103/PhysRevE.108.024404.
During embryonic development, structures with complex geometry can emerge from planar epithelial monolayers; studying these shape transitions is of key importance for revealing the biophysical laws involved in the morphogenesis of biological systems. Here, using the example of normal proliferative monkey kidney (COS) cell monolayers, we investigate global and local topological characteristics of this model system in dependence on its shape. The obtained distributions of cells by their valence demonstrate a difference between the spherical and planar monolayers. In addition, in both spherical and planar monolayers, the probability of observing a pair of neighboring cells with certain valences depends on the topological charge of the pair. The zero topological charge of the cell pair can increase the probability for the cells to be the nearest neighbors. We then test and confirm that analogous relationships take place in a more ordered spherical system with a larger fraction of 6-valent cells, namely, in the nonproliferative epithelium (follicular system) of ascidian species oocytes. However, unlike spherical COS cell monolayers, ascidian monolayers are prone to nonrandom agglomeration of 6-valent cells and have linear topological defects called scars and pleats. The reasons for this difference in morphology are discussed. The morphological peculiarities found are compared with predictions of the widely used vertex model of epithelium.
在胚胎发育过程中，具有复杂几何形状的结构可以从平面上皮单层中出现；研究这些形状转变对于揭示生物系统形态发生中涉及的生物物理规律至关重要。在这里，我们以正常增殖的猴肾 (COS) 细胞单层为例，研究了该模型系统在其形状依赖性方面的全局和局部拓扑特征。通过细胞价的分布证明了球形和平面单层之间存在差异。此外，在球形和平面单层中，观察到具有一定价的相邻细胞对的概率取决于对的拓扑电荷。细胞对的零拓扑电荷可以增加细胞成为最近邻的概率。然后，我们测试并证实，在具有更大比例 6 价细胞的更有序的球形系统中，即，在海鞘物种卵母细胞的非增殖上皮（滤泡系统）中，类似的关系也会发生。然而，与球形 COS 细胞单层不同，海鞘单层容易发生 6 价细胞的非随机聚集，并且具有称为疤痕和褶皱的线性拓扑缺陷。讨论了这种形态差异的原因。所发现的形态特征与广泛使用的上皮顶点模型的预测进行了比较。
