The migration areas in the vertebrate brain form is early stages a network consisting of transversal bands and longitudinal columns. In the rhomben-cephalon there are 4 longitudinal columns. The dorsal one which gives rise to the "somato-sensory column", ceases at the isthmus fold. The ventral one which gives rise to the "somato-motor column" continues rostrally only to the di-mesencephalic border. The other 2 columns give rise to the "viscero-sensory" and "viscero-motor columns" from the rest of the mesencephalon, the whole of the diencephalon and the telencephalon. The transversal rhombencephalic bands correspond to the cranial nerves and probably to the rhombomeres.