Dynamics of cell rearrangements during tissue morphogenesis

In developing tissues, embryos, and cell aggregates, individual cells proliferate, migrate, and rearrange, giving rise to coordinated collective behaviors and complex morphogenetic patterns. Understanding these emergent dynamics is essential for revealing the biomechanical principles that govern tissue morphogenesis. Computational modeling, particularly through agent-based models (ABMs) that treat each cell as a mechanical and biological agent, provides a powerful means to link cell-level mechanics to tissue-scale organization. Among key morphogenetic processes, convergent extension, which is tissue elongation along one axis and contraction along the orthogonal one, is driven by anisotropic and active T1 transitions, wherein cells preferentially exchange neighbors along a specific direction. In this work, we employ the Morphodynamic Network Model (MNM), a recently developed ABM framework, to study convergent extension dynamics. The MNM distinguishes between activity-driven and energetically driven cell rearrangements, enabling a mechanistic understanding of how directional T1 transitions produce large-scale anisotropic deformations and revealing the physical principles underlying active tissue elongation.