Efficient absorption of nutrients by the intestine is essential for life. In mammals and birds, convolution of the intestinal surface into finger‐like projections called villi is an important adaptation that ensures the massive surface area for nutrient contact that is required to meet metabolic demands. Each villus projection serves as a functional absorptive unit: it is covered by a simple columnar epithelium that is derived from endoderm and contains a mesodermally derived core with supporting vasculature, lacteals, enteric nerves, smooth muscle, fibroblasts, myofibroblasts, and immune cells. In cross section, the consistency of structure in the billions of individual villi of the adult intestine is strikingly beautiful. Villi are generated in fetal life, and work over several decades has revealed that villus morphogenesis requires substantial “crosstalk” between the endodermal and mesodermal tissue components, with soluble signals, cell–cell contacts, and mechanical forces providing specific dialects for sequential conversations that orchestrate villus assembly. A key part of this process is the formation of subepithelial mesenchymal cell clusters that act as signaling hubs, directing overlying epithelial cells to cease proliferation, thereby driving villus emergence and simultaneously determining the location of future stem cell compartments. Interestingly, distinct species‐specific differences govern how and when tissue‐shaping signals and forces generate mesenchymal clusters and control villus emergence. As the details of villus development become increasingly clear, the emerging picture highlights a sophisticated local self‐assembled cascade that underlies the reproducible elaboration of a regularly patterned field of absorptive villus units.

中文翻译：

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肠绒毛设计图：需要特定于物种的组装。

肠道有效吸收营养对于生命至关重要。在哺乳动物和鸟类中，肠表面卷积成称为绒毛的手指状突起是一种重要的适应措施，可确保满足代谢需求所需的大量养分接触表面积。每个绒毛投射物都充当功能性吸收单位：它被一个简单的柱状上皮覆盖，该上皮源自内胚层，并包含中胚层衍生的核心，具有支持的脉管系统，乳腺，肠神经，平滑肌，成纤维细胞，成肌纤维细胞和免疫细胞。在横截面中，成年肠的数十亿个绒毛中的结构一致性非常美丽。绒毛在胎儿生命中产生，数十年来的工作表明，绒毛的形态发生需要内胚层和中胚层组织成分之间发生大量的“串扰”，可溶性信号，细胞间接触以及机械力为编排绒毛的顺序对话提供了特定的方言。该过程的关键部分是上皮下间充质细胞簇的形成，它们充当信号枢纽，指导上皮细胞停止增殖，从而驱动绒毛的出现并同时确定未来干细胞区室的位置。有趣的是，不同的物种特异性差异决定着组织塑造信号和力如何以及何时产生间充质簇并控制绒毛的出现。随着绒毛发展的细节越来越清晰，