In multicellular systems, cells communicate with adjacent cells to decide their positions and fates. Cellular arrangement in space is thus important for development. Here we developed a multicellular morphology model based on the phase-field method so that we can incorporate precise geometric constrains. We applied the model to examine cell arrangement in the 4-cell stage embryo of nematodes, and succeeded in reproducing cell arrangements observed in vivo, including an arrangement which has not been explained before. Our cell morphology model predicted that the amount of extra-embryonic space (ES), the empty space within the eggshell not occupied by embryonic cells, affects cell arrangement in a manner dependent on the local contour. The prediction was validated experimentally as increasing the ES did change the cell arrangement in the Cenorhabditis elegans embryo. Overall, our analyses characterized the roles of new geometrical contributors, namely the amount of ES and the local contour, to cell arrangements. These factors should be considered in all multicellular systems, including human being.
This work was collaborated with K. Yamamoto (Kanagawa Institute of Technology) and A. Kimura (National Institute of Genetics) and is published in Development.