瑞士日内瓦大学Michel C. Milinkovitch团队近期取得重要工作进展，他们研究提出，鳄鱼头部鳞片通过压缩折叠形成自组织结构。相关研究成果2024年12月11日在线发表于《自然》杂志上。

据介绍，羊膜附属物构成了一组不同的微器官，包括羽毛、毛发和鳞片。这些结构通常发展为基因控制的单元，其空间模式来自具有集成机械反馈的自组织化学图灵系统。多边形鳄鱼头鳞片看似纯粹的机械图案为这种范式提供了一个例外。然而，驱动这种模式的机械应力场的性质和起源尚不清楚。

使用精确的卵内静脉注射表皮生长因子蛋白，研究人员产生了头部皮肤基本卷曲的尼罗鳄胚胎，以及具有类似于凯门鳄的较小多边形头部鳞片的幼体。然后，研究人员使用光片荧光显微镜来量化，胚胎组织层几何形状、胶原蛋白结构和增殖细胞的空间分布。

利用这些数据，研究人员建立了一个现象学三维机械生长模型，该模型概括了鳄鱼头鳞片的正常和实验性修改模式。实验和数值模拟表明，鳄鱼头鳞片通过压缩折叠自组织，起源于真皮与表皮硬度不同的近乎均匀的皮肤生长。

总之，这一实验和理论形态空间分析表明，胚胎生长和皮肤层材料特性的变化提供了一种简单的演化机制，在鳄鱼物种中产生了头部鳞片模式的多样性。

附：英文原文

Title: Self-organized patterning of crocodile head scales by compressive folding

Author: Santos-Durn, Gabriel N., Cooper, Rory L., Jahanbakhsh, Ebrahim, Timin, Grigorii, Milinkovitch, Michel C.

Issue&Volume: 2024-12-11

Abstract: Amniote integumentary appendages constitute a diverse group of micro-organs, including feathers, hair and scales. These structures typically develop as genetically controlled units1, the spatial patterning of which emerges from a self-organized chemical Turing system2,3 with integrated mechanical feedback4,5. The seemingly purely mechanical patterning of polygonal crocodile head scales provides an exception to this paradigm6. However, the nature and origin of the mechanical stress field driving this patterning remain unclear. Here, using precise in ovo intravenous injections of epidermal growth factor protein, we generate Nile crocodile embryos with substantially convoluted head skin, as well as hatchlings with smaller polygonal head scales resembling those of caimans. We then use light-sheet fluorescence microscopy to quantify embryonic tissue-layer geometry, collagen architecture and the spatial distribution of proliferating cells. Using these data, we build a phenomenological three-dimensional mechanical growth model that recapitulates both normal and experimentally modified patterning of crocodile head scales. Our experiments and numerical simulations demonstrate that crocodile head scales self-organize through compressive folding, originating from near-homogeneous skin growth with differential stiffness of the dermis versus the epidermis. Our experiments and theoretical morphospace analyses indicate that variation in embryonic growth and material properties of skin layers provides a simple evolutionary mechanism that produces a diversity of head-scale patterns among crocodilian species.

DOI: 10.1038/s41586-024-08268-1

Source: https://www.nature.com/articles/s41586-024-08268-1