Epithelial convergent extension as a tuning process.

Self-tuning-the ability of disordered systems to develop desired collective behaviors by tuning internal couplings in response to feedback-has recently emerged as a powerful framework for understanding adaptation in amorphous solids, mechanical metamaterials, and electrical networks. These systems can learn desired responses, encode memory, and robustly reorganize under repeated stimuli, much like artificial neural networks but without requiring processors to adjust their weights. Here, we extend this paradigm to morphogenesis and show that it is useful to view the epithelium as tunable matter and epithelial convergent extension (CE) as a self-tuning process. Using a vertex model with active interfacial tensions, we systematically compare distinct tension-update processes, including externally imposed shear, global gradient descent optimization, and decentralized local feedback rules. We find that while all methods can generate tissue elongation, only a local orientation- and length-sensitive rule reproduces key experimental features of CE with reasonable fidelity. These features include supracellular actomyosin pattern formation, cell shape changes, and junctional alignment. In contrast, global optimization produces homogeneous, nearly isotropic tension patterns and tissue states that are less robust to force perturbations. By interpreting CE through the lens of tuning, our framework bridges the physics of tunable matter with developmental biology, revealing how simple, local rules enable tissues to efficiently orchestrate complex morphogenetic outcomes through decentralized mechanical feedback and adaptation.