Hydramorphogenesis as phase-transition dynamics

Abstract

ABSTRACTWe utilize whole-bodyHydraregeneration from a small tissue segment to develop a physics framework for animal morphogenesis. Introducing experimental controls over this process, an external electric field and a drug that blocks gap junctions, allows us to characterize the essential step in the morphological transition - from a spherical shape to an elongated spheroid. We find that spatial fluctuations of the Ca2+distribution in theHydra’stissue drive this transition and construct a field-theoretic model that explains the morphological transition as a first-order-like phase transition resulting from the coupling of the Ca2+field and the tissue’s local curvature. Various predictions of this model are verified experimentally.