Morphogenesis Control in Avian Gastrulation

Hosts: Kees Weijer & Rastko Sknepnek

Venue: MSI Small Lecture Theatre, SLS

Abstract: During gastrulation, coordinated cell behaviours sculpt the vertebrate body plan. We previously quantified the tissue flows emerging from these multicellular dynamics in terms of dynamic attractors and repellers (M. S. et al. PNAS, 2020). We also linked cell behaviours to self-organized tissue flows using a theoretical model whereby gastrulation results from a mechanosensitive-myosin instability (M. S. et al. Sci. Adv., 2023). Experiments and modelling determined that the attractor's shape depends on initial myosin patterns and cell ingression (M. C. et al. Sci. Adv., 2023). We now focus on deciphering the mechanistic origins of morphogenetic repellers. By extending our model, we find that one repeller arises from the tug-of-war between the embryo and the extraembryonic tissue, while the second repeller self-organizes solely from the convergent extension of the mesoderm. To test these predictions, we developed ex-ovo cultures, enabling the manipulation of the embryonic geometry in parallel with live imaging and flow quantification. By applying mechanical and chemical interventions inspired by our model, we were able to eliminate both repellers independently in chick embryos. Overall, our integrated modelling and perturbation approach reveals how coordinated cell behaviours sculpt a biomechanical landscape of attractors/repellers guiding avian gastrulation, elucidating the role of extraembryonic epiboly forces, embryonic apical constriction, ingression, and mechanosensitive myosin activity.