Neural crest rules the gut The neurons and glial cells that regulate gut function derive from neural crest cells that emerge from the developing neural tube. Lasrado et al. used single-cell transcriptomics and mosaic mutagenesis to follow how the enteric nervous system is built in mice. Overlapping expression of regulatory programs supports dynamic determination of cell fates, with the developing neurons organized by clonal lineages. The clonal build model may explain how gut motility is coordinated in sequential segments and gut secretion is coordinated with motility. Science , this issue p. 722