Genetic ablation reveals that the roof plate is essential for dorsal interneuron specification

During neural development in vertebrates, a spatially ordered array of neur ons is generated in response to inductive signals derived from localized or ganizing centres, One organizing centre that has been proposed to have a ro le in the control of neural patterning is the roof plate, To define the con tribution of signals derived from the roof plate to the specification of ne uronal cell types in the dorsal neural tube, we devised a genetic strategy to ablate the roof plate selectively in mouse embryos, Embryos without a ro of plate lack all the interneuron subtypes that are normally generated in t he dorsal third of the neural tube. Using a genetically based lineage analy sis and in vitro assays, we show that the loss of these neurons results fro m the elimination of nonautonomous signals provided by the roof plate, Thes e results reveal that the roof plate is essential for specifying multiple c lasses of neurons in the mammalian central nervous system.