title: Developmental relationships between trigeminal ganglia and trigeminal motoneurons in chick embryos. II. Ganglion axon ingrowth guides motoneuron migration.
abstract: In the chick embryo the trigeminal (V) sensory ganglion cells send axons into the metencephalon a few hours before the V motoneurons migrate from the midline to form a lateral nucleus adjacent to the ingrowing sensory axons. This relationship suggests that the ganglion axons may influence the initiation and direction of V motoneuron migration. In the present experiment the development of the ganglion axons was retarded by removing the neural crest anlage of the V ganglion. Subsequently, V ganglion cells which were derived from the ectodermal placode anlage sent axons into the metencephalon up to 2 days later than normal. The lateral migration of the V motoneurons was similarly delayed, commencing only after the central axons from the placodal ganglia penetrated the metencephalon. This study demonstrates that the presence of V ganglion perikarya alone is not sufficient to guide the appropriate migration of V motoneurons. This migration occurs only after the axons from the V sensory ganglion cells have penetrated the brainstem.
mesh_terms: D000818:Animals; D001369:Axons / Q000502:physiology; D002465:Cell Movement; D002642:Chick Embryo; D004627:Embryonic Induction; D009046:Motor Neurons / Q000502:physiology*; D009432:Neural Crest / Q000502:physiology; D011149:Pons / Q000196:embryology; D012668:Trigeminal Ganglion / Q000196:embryology*; D014276:Trigeminal Nerve / Q000196:embryology*