Oded Agam - Field-Theoretical Perspectives on Morphogenesis in Hydra Regeneration

This talk was part of the Workshop on "Extremal Statistics in Biology" held at the ESI June 10 - 13, 2025.
Animal morphogenesis is the process by which organisms develop their mature body forms through structural changes. Hydra, a small freshwater organism, serves as an ideal model for studying morphogenesis due to its simple bilayer structure (~10⁵ cells), remarkable regenerative capacity, and robust development under manipulation. When a small tissue fragment from Hydra’s gastric region is excised, it first folds into a hollow sphere and, within 1–2 days, regenerates into a whole animal without significant cell division. The primary morphological transition—from an initial spherical shape to a stable cylindrical structure—occurs rapidly after a long period of morphological stasis.

In this talk, I will present a field-theoretical framework describing this transition, based on the coupling between calcium ion fluctuations and local tissue curvature. This coupling defines a morphological potential, which calculations show to be a tilted double-well: one minimum representing the spherical state, the other an elongated, tube-like structure. The model predicts that the morphological transition resembles a first-order-like phase transition, a prediction supported by instanton-based estimates of transition times compared to experiments. To further validate the model, I will show that periodic modulation of the morphological potential induces stochastic resonance, experimentally observed as stochastic swings in tissue shape.

Видео Oded Agam - Field-Theoretical Perspectives on Morphogenesis in Hydra Regeneration канала Erwin Schrödinger International Institute for Mathematics and Physics (ESI)