Berking Stefan
Zoological Institute, University of Cologne, Weyertal 119, D-50923 Köln, Germany.
J Theor Biol. 2007 Jun 7;246(3):477-90. doi: 10.1016/j.jtbi.2007.01.008. Epub 2007 Jan 20.
Polyps of Anthozoa usually display bilateral symmetry with respect to their mouth opening, to their pharynx, and in particular to the arrangement of their mesenteries. Mesenteries, which are endodermal folds running from the apical to the basal end of the body, subdivide the gastric cavity into pouches. They form in a bilateral symmetric sequence. In this article I propose that early in polyp development the endoderm subdivides successively into three different types of compartments. A mesentery forms at the border between compartments. Two of the compartments are homologous to those of Scyphozoa. They form by mutual activation of cell states that locally exclude each other. The third compartment leads to siphonoglyph formation and is an evolutionary innovation of the Anthozoa. The mechanism that controls the number and spatial arrangement of the third type of compartment changes the radial symmetry into a bilateral one and occasionally into a different one. The dynamics of its formation indicate an activator-inhibitor mechanism. Computer models are provided that reproduce decision steps in the generation of the mesenteries.
珊瑚纲动物的息肉通常在口部开口、咽部，特别是隔膜的排列方面呈现双侧对称。隔膜是从身体顶端延伸至基部的内胚层褶皱，将胃腔分隔成小室。它们以双侧对称的顺序形成。在本文中，我提出在息肉发育早期，内胚层会依次细分为三种不同类型的隔室。隔膜在隔室之间的边界处形成。其中两个隔室与钵水母纲动物的隔室同源。它们通过局部相互排斥的细胞状态的相互激活而形成。第三个隔室导致口道沟的形成，是珊瑚纲动物的一项进化创新。控制第三种隔室数量和空间排列的机制将辐射对称转变为双侧对称，偶尔也会转变为另一种对称形式。其形成动态表明存在一种激活-抑制机制。提供了计算机模型，该模型再现了隔膜生成过程中的决策步骤。
