Local nonpermissive and oriented permissive cues guide vestibular axons tothe cerebellum

Information that originates from peripheral sensory organs is conveyed by a xons of cephalic sensory cranial ganglia connecting the sensory organs to a ppropriate central targets in the brain. Thus, the establishment of correct axonal projections by sensory afferents is one of the most important issue s in neural development. Previously, we examined the development of the ves tibular nerve that originates from the VIIIth ganglion using a hat wholemou nt preparation of the rat hindbrain and developed an in vitro, culture prep aration that can recapitulate vestibular nerve development (Tashiro. Y., En do, T., Shirasaki, R., Miyahara, M., Heizmann, C. W. and Murakami, F. (2000 ) J. Comp. Neurol, 417, 491-500), Both in vivo and in vitro, the ascending branch of the VIIIth ganglion projecting to the cerebellum reaches the base of the cerebellar primordium and starts to splay out towards the rhombic l ip, apparently avoiding the ventral metencephalon, We now examine the natur e of cues that guide vestibulocerebellar axons by applying various manipula tions to the flat whole-mount in vitro preparation. Our observations sugges t that local nonpermissive cues and oriented cues play a pivotal role in th e guidance of vestibular axons to their central target.