Folding is an important way by which epithelia are sculpted into three-dimensional shapes during development. Recent studies have integrated quantitative image analysis and physical modeling to uncover contributing mechanisms. It is becoming clear that folding processes often employ multiple mechanisms of force generation. Here, we review divergent modes of epithelial folding. We argue that, in many cases, several mechanisms interact at different time-scales and length-scales to generate a fold. In other cases, very similar folds are generated by different folding mechanisms. How one (or a specific combination of) mechanism(s) might be advantageous in one case versus another is not understood, and future work using quantitative analyses and modeling will be required to determine reasons for distinct modes of folding.

中文翻译：

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在形态发生过程中促进上皮折叠的发散和组合机械策略。

折叠是上皮在发育过程中被雕刻成三维形状的一种重要方式。最近的研究已经集成了定量图像分析和物理模型，以发现其作用机理。越来越清楚的是，折叠过程经常采用多种力产生机制。在这里，我们审查上皮折叠的分歧模式。我们认为，在许多情况下，几种机制在不同的时间尺度和长度尺度上相互作用以产生折叠。在其他情况下，通过不同的折叠机构会产生非常相似的折叠。尚不了解一种（或一种）特定机制在一种情况下相对于另一种机制的优势，因此，需要使用定量分析和建模的未来工作来确定不同折叠方式的原因。