Oligodendrocyte transcription factor-1 (Olig1) and Olig2, which have been implicated in oligodendrogenesis, are expressed in the region of the ventral ventricular zone of late embryonic spinal cord where oligodendrocyte progenitors appear. Olig3 is transiently expressed in different types of progenitors of embryonic central nervous system and then disappears in the course of development. In adult, expression of Olig3 is primarily detected in neural tissues.
Olig1 and Olig2 are basic-helix-loop-helix (bHLH) transcription factors expressed in the motor neuron progenitor (pMN) domain of the spinal cord that generates motor neurons and oligodendrocytes. Olig1 is involved in the development and maturation of oligodendrocytes. Olig2 is required for oligodendrocyte and motor neuron specification in the spinal cord.