The primitive streak, a transient embryonic structure, marks bilateral symmetry in mammalian and avian embryos and helps confer anterior-posterior and dorsal-ventral spatial information to early differentiating cells during gastrulation. Its recapitulation in vitro may facilitate derivation of tissues and organs with in vivo–like complexity. Proper understanding of the primitive streak and what it entails in human development is key to achieving such research objectives. Here we provide an overview of the primitive streak and conclude that this structure is neither conserved nor necessary for gastrulation or early lineage diversification. We offer a model in which the primitive streak is viewed as part of a morphologically diverse yet molecularly conserved process of spatial coordinate acquisition. We predict that recapitulation of the primitive streak is dispensable for development in vitro.

中文翻译：

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通过原肠胚形成羊膜体的原始条纹和细胞原理

原始条纹是一种短暂的胚胎结构，标志着哺乳动物和鸟类胚胎的双边对称性，并有助于在原肠胚形成过程中为早期分化细胞提供前后和背腹空间信息。它在体外的概括可能有助于衍生出具有类似体内复杂性的组织和器官。正确理解原始条纹及其对人类发展的影响是实现此类研究目标的关键。在这里，我们提供了原始条纹的概述，并得出结论，这种结构对于原肠胚形成或早期谱系多样化既不保守也不必需。我们提供了一个模型，其中原始条纹被视为空间坐标获取的形态多样但分子保守过程的一部分。