Modeling cell shape changes in the zebrafish embryo using a 3D vertex model*

Programmed cell shape changes in a developing embryo are essential for building many functional organs such as the neural tube, gut, and heart. Here we focus on Kupffer’s vesicle (KV) in the zebrafish embryo as a model organ, as it undergoes programmed asymmetric cell shape changes to establish the left-right axis of the embryo. A 3D Voronoi model, where the degrees of freedom are the cell centers, has previously demonstrated that the tailbud tissue surrounding the KV can generate drag forces and drive cell shape changes in KV. However, recent work has suggested that a 3D Vertex model, where the degrees of freedom are the vertices between cells, better captures realistic shape changes in systems with heterogenous architectures like the KV. Here we employ the 3D Vertex model to capture the propulsion of KV through tailbud tissue and study cell shape changes. We investigate KV cell shapes and cell distribution for a range of values of tailbud tissue fluidity and KV propulsion velocity, and compare to experiments. We further examine how the left-right asymmetric tailbud tissue mechanics, notochord-KV interaction, and differential propulsion of cells in KV influence the cell shape changes in KV. Our findings provide insight into the physical mechanisms that regulate organogenesis, and may help identify new targets for therapeutics.