Gap junctions in the developing nervous system.

Cell-cell interactions are important in the development of the nervous system. Gap junctions (GJs) form direct intercellular channels that permit diffusion of ions and small molecules and thus cells linked by GJs can influence each other's properties or behavior either through transmission of electrical signals or through transfer of signaling molecules. In the developing nervous system, widespread GJ communication occurs at the time of neural induction, but in the adult nervous system it is much more restricted. In addition, certain events in neural development appear to involve the formation of transient junctional connections. This review examines briefly four aspects of neural development in which GJs may be involved, namely, neurulation, regional differentiation, migration, and axon guidance.