Neuroblasts in the subventricular zone of the walls of the lateral ventricle in the brain of young and adult rodents migrate into the olfactory bulb where they differentiate into local interneurons. These cells move closely associated with each other, forming chains without radial glial or axonal guidance. The migrating neuroblasts express PSA-NCAM on their surface and PSA residues are crucial for cell-cell interaction during chain migration. This migration occurs throughout the lateral wall of the lateral ventricle, where the precursors form an extensive network of chains. Cells remain organized as chains until they reach the olfactory bulb, where they disperse organized as chains until they reach the olfactory bulb, where they disperse radially as individual cells. Chain migration defines a novel form of neuronal precursor translocation which is based on homotypic interactions between cells.