The growth and differentiation of neural precursor cells in the central nervous system (CNS) are regulated by their response to polypeptide growth factors which interact with specific transmembrane receptor tyrosine kinases (RTKs). We demonstrate that rat oligodendrocyte-type 2 astrocyte (O-2A) glial progenitor cells, precursors of the myelin-forming cells in the CNS, express the transmembrane RTK c-kit, the gene product of the murine dominant white spotting (W) locus and receptor for stem cell factor. Expression of c-kit transcripts and immunoreactive protein is lost when O-2A progenitors differentiate into post-mitotic oligodendrocytes. Analysis of developing rat brain revealed an increase in the expression of c-kit transcripts between postnatal days 10 and 12, a window of time preceding the emergence of oligodendrocytes and the onset of myelination in vivo. Expression of c-kit in vitro and in vivo suggests a role for this receptor and its ligand during oligodendrocyte development.