The pancreas, a gland that secretes digestive juices into the stomach and insulin into the blood, develops from two endodermal buds. In mice embryos,fibroblast growth factors (FGFs) secreted by the pancreatic mesenchyme control the development of these buds, but how does the pancreatic mesenchyme form?Manfroid and colleagues now show that, in zebrafish embryos, reciprocal endoderm-mesoderm interactions mediated by FGFs control pancreas development(see p. 4011). The researchers identify an area next to the ventral pancreatic bud - the pancreatic lateral plate mesoderm (LPM) - that corresponds to the pancreatic mesenchyme in mice and that is essential for ventral bud development. They show for the first time that transient expression of fgf24 in the endodermal precursor of the ventral bud patterns the pancreatic LPM and report that subsequent expression of fgf10 and fgf24 by the pancreatic LPM controls the specification and growth of the ventral pancreas. Thus, they conclude, sequential signalling between the endoderm and mesoderm drives pancreas development in zebrafish.