We present in vivo observations of chicken embryo development which show that the early chicken embryo presents a principal structure made out of concentric rings and a secondary structure composed of radial sectors. During development, physical forces deform the main rings into axially directed, antero-posterior tubes, while the sectors roll up to form cylinders that are perpendicular to the antero-posterior axis. As a consequence, the basic structure of the chicken embryo is a series of encased antero-posterior tubes (gut, neural tube, body envelope, amnion, chorion) decorated with smaller orifices (ear duct, eye stalk, nasal duct, gills, mouth) forming at right angles to the main body axis. We argue that the second-order divisions reflect the early pattern of cell cleavage, and that the transformation of radial and orthoradial lines into a body with sensory organs is a generic biophysical mechanism more general than the chicken embryo.

我们提出了鸡胚发育的体内观察结果，表明早期鸡胚呈现出由同心环组成的主要结构和由径向扇区组成的二级结构。在开发过程中，物理力使主环变形为轴向定向的前后管，而扇区卷起形成垂直于前后轴的圆柱体。因此，鸡胚的基本结构是一系列包裹的前后管（肠、神经管、体包膜、羊膜、绒毛膜），上面装饰着较小的孔（耳管、眼柄、鼻管、鳃、嘴) 形成与主体轴线成直角。我们认为二级分裂反映了细胞分裂的早期模式，