The brainstem depends on Lmx1a/b, Gdf7 and bHLH genes. The choroid plexus is unique, forming in the brainstem. The choroid plexus depends on Lmx1a/b and Gdf7 (A), and is replaced for the roof plate in the spinal cord (C,D). Downstream are bHLH genes that have been identified in the Atoh1 (A,B), Neurog1 (A,B′), Neurog2, Neurod1, Ascl1, Olig3 and Ptf1a. Certain expression is unique for the vestibular and auditory nuclei: Ptf1a is a duplication of ventral genes that are replaced by more rostral genes (Neurog1, Ascl1). Lmx1b, Fgf8 and Wnt1 are common cerebellums (CB) of r0. In the absence of Lmx1a/b and choroid plexus, no cochlear nuclei form and vestibular, trigeminal and solitary tract interact across the roof plate (C,D). dV, trigeminal fibers; FBM, facial branchial motoneurons; ST, solitary tract; V, VII, VIII, IX, X, afferent fibers; Vmn, trigeminal motoneurons; Vsm, trigeminal nucleus. Modified after [28,82,157].