Expression of olig2 in retinal progenitor cells.

Olig2 is a basic helix-loop-helix transcription factor that is specifically expressed in oligodendrocyte precursors in the central nervous system. Owing to the absence of oligodendrocytes in the retina, however, the role of olig2 in retinal development remains unclear. In the present study, we demonstrated for the first time that olig2 is expressed in embryonic and postnatal mouse retina. Interestingly, a subset of the bromodeoxyuridine-positive cells expressed olig2 in the embryonic retina. On the other hand, olig2-positive cells did not express nestin, neuron-specific class III beta-tubulin, neurofilament, or various retinal cell-type-specific markers. These results suggest that olig2 is involved in the maintenance of the undifferentiated state of retinal progenitor cells.