How are the numbers of different cell types matched together during tissue development? The nervous system has provided an excellent model system for understanding this question as it contains two main classes of cell types, neurons and glia. Presynaptic neurons are believed to be precisely matched to their postsynaptic target cells, either muscle cells or other neurons, by a competition for limiting amounts of target-derived neurotrophic factors (Purves 1988). The number of some glial cells that survive also appears to depend on a competition for neuron-derived survival signals. In particular, the number of myelinating glial cells that survive appears to be precisely matched during development to the number and lengths of axons requiring myelination. Here we review recent evidence that axons are the master regulators of oligodendrocyte development.
Oligodendrocytes are postmitotic cells that develop from oligodendrocyte...
