In Cnidaria, modes of gastrulation to produce the two body layers vary greatly between species. In the hydrozoan species Clytia hemisphaerica gastrulation involves unipolar ingression of presumptive endoderm cells from an oral domain of the blastula, followed by migration of these cells to fill the blastocoel with concomitant narrowing of the gastrula and elongation along the oral-aboral axis. We developed a 2D computational boundary model capable of simulating the morphogenetic changes during embryonic development from early blastula stage to the end of gastrulation. Cells are modeled as polygons with elastic membranes and cytoplasm, colliding and adhering to other cells, and capable of forming filopodia. With this model we could simulate compaction of the embryo preceding gastrulation, bottle cell formation, ingression, and intercalation between cells of the ingressing presumptive endoderm. We show that embryo elongation is dependent on the number of endodermal cells, low endodermal cell-cell adhesion, and planar cell polarity (PCP). When the strength of PCP is reduced in our model, resultant embryo morphologies closely resemble those reported previously following morpholino-mediated knockdown of the core PCP proteins Strabismus and Frizzled. Based on our results, we postulate that cellular processes of apical constriction, compaction, ingression, and then reduced cell-cell adhesion and mediolateral intercalation in the presumptive endoderm, are required and when combined, sufficient for Clytia gastrulation.

在猪唇草中，产生两个身体层的胃化方式在物种之间差异很大。在水生动物物种Clytia hemisphaerica中胃胚化涉及推定的内胚层细胞从囊胚的口腔域单极进入，随后这些细胞迁移以填充囊胚腔，伴随着胃扁桃体变窄和沿口腔-胸骨轴的伸长。我们开发了一个二维计算边界模型，该模型能够模拟从胚囊早期到胃形成末期胚胎发育过程中的形态发生变化。细胞被建模为具有弹性膜和细胞质，与其他细胞碰撞并粘附并能够形成丝状伪足的多边形。使用此模型，我们可以模拟胚芽压实，瓶胚细胞形成，进入以及进入的推测内胚层细胞之间的嵌入之前的胚紧实。我们证明了胚胎的伸长取决于内胚层细胞的数量，低内胚层细胞间粘附力和平面细胞极性（PCP）。当PCP的强度在我们的模型中降低时，最终的胚胎形态与先前报道的吗啉代介导的核心PCP蛋白斜视和卷曲的敲除后的形态相似。根据我们的研究结果，我们推测，在假定的内胚层中，需要先进行顶突收缩，压实，进入，然后减少细胞间粘附和中外侧插入的细胞过程，并且将它们结合起来足以幽门螺杆菌。