Dorsoventral patterning and oligodendroglial specification in the developing central nervous system.

While the bulk of oligodendendrocytes are generated postnatally in rodents, it is now clear that the first oligodendrocytes are born during midembryonic development. Recent studies imply that the first oligodendrocytes to appear are specified concurrently with certain neuronal subtypes. In addition, patterning molecules known to confer positional information on neural tissues during development, such as sonic hedgehog and bone morphogenetic proteins, have also been implicated in the specification of glial fate. This review discusses some of the recent advances in our knowledge of how oligodendrocytes are generated and the mechanisms by which this might occur in the developing brain and spinal cord.