A mechanical wave travels along a genetic guide to drive the formation of an epithelial furrow during Drosophila gastrulation.
                            
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                                CRY2/CIB1
                            
                            
                                
                                    D. melanogaster in vivo
                                
                            
                            
                                Control of cytoskeleton / cell motility / cell shape
                            
                                Developmental processes
                            
                            
                            
                            
                            
                        
                        
                        
                        
                            Abstract:
                            Epithelial furrowing is a fundamental morphogenetic process during gastrulation, neurulation, and body shaping. A furrow often results from a fold that propagates along a line. How fold formation and propagation are controlled and driven is poorly understood. To shed light on this, we study the formation of the cephalic furrow, a fold that runs along the embryo dorsal-ventral axis during Drosophila gastrulation and the developmental role of which is still unknown. We provide evidence of its function and show that epithelial furrowing is initiated by a group of cells. This cellular cluster works as a pacemaker, triggering a bidirectional morphogenetic wave powered by actomyosin contractions and sustained by de novo medial apex-to-apex cell adhesion. The pacemaker's Cartesian position is under the crossed control of the anterior-posterior and dorsal-ventral gene patterning systems. Thus, furrow formation is driven by a mechanical trigger wave that travels under the control of a multidimensional genetic guide.