In this comprehensive project, we have identified the molecular profiles of the submucosal neuron classes of the small intestine of mice. We determine how they connect with each other and to other gut-cells. Surprisingly, a close connection to enterochromaffin cells was found with all three major submucosal neuron classes, indicating sensory abilities not only by classical intrinsic primary afferent neurons, but also of secretomotor neuron types. The study also revealed that submucosal neurons are generated during fetal development through a stepwise differentiation process akin to the principle we previously uncovered for myenteric neurons. Thus, the whole ENS appears to form from an initial bifurcation at neurogenesis followed by postmitotic identity conversions.