Emergence of a geometric pattern of cell fates from tissue-scale mechanics in the Drosophila eye

Pattern formation of biological structures involves the arrangement of different types of cells in an ordered spatial configuration. In this study, we investigate the mechanism of patterning the Drosophila eye into a precise triangular grid of photoreceptor clusters called ommatidia. Previous studies had led to a long-standing biochemical model whereby a reaction-diffusion process is templated by recently formed ommatidia to propagate a molecular prepattern across the eye epithelium. Here, we find that the templating mechanism is instead, mechanical in origin; newly born columns of ommatidia serve as a template to spatially pattern cell flows that move the cells in the epithelium into position to form each new column of ommatidia. Cell flow is generated by a pressure gradient that is caused by a narrow zone of cell dilation precisely positioned behind the growing wavefront of ommatidia. The newly formed lattice grid of ommatidia cells are immobile, deflecting and focusing the flow of ot...生物结构的模式形成，指不同类型细胞按照有序空间构型进行排布的过程。本研究聚焦于果蝇（Drosophila）复眼的模式形成机制，该机制旨在将复眼构建为光感受器簇构成的精确三角网格结构，这类结构被称为小眼（ommatidia）。过往研究提出了一套沿用已久的生化模型：该模型提出，反应扩散（reaction-diffusion）过程以新近形成的小眼为模板，在眼上皮（eye epithelium）中传播分子预模式。本研究发现，该模板化机制实则起源于力学层面：新生的小眼柱体充当模板，对细胞流动进行空间模式塑造，驱使眼上皮内的细胞移动至指定位置，以形成每一组新的小眼柱体。细胞流动由压力梯度驱动，而该压力梯度源于小眼生长波前后方精准定位的狭窄细胞扩张区域。新形成的小眼细胞晶格网格处于静止状态，可偏转并汇聚……