Formation of the head fold (HF), the first three-dimensional structure to form in the embryo, is a crucial event that initiates heart, foregut and brain development. Although the molecular factors involved in HF development are becoming known, the biophysical mechanisms governing this transformation have yet to be investigated. Now, on , Larry Taber and colleagues combine experimental and modelling approaches to determine the forces that drive HF formation in chick embryos. They generated a computational model for HF formation, and by inducing three distinct morphogenetic mechanisms – convergent extension in the neural plate (NP), cell wedging along the anterior NP border, and cell shaping outside the NP – they were able to simulate HF formation in this model. By comparing the changes in tissue morphology, mechanical strains and regional tissue stresses observed in the model with those measured experimentally in ex ovo embryos, the authors confirm that these three modelled morphogenetic mechanisms can alone provide the forces that drive HF formation.
