SPINAL-CORD OLIGODENDROCYTES DEVELOP FROM VENTRALLY DERIVED PROGENITOR CELLS THAT EXPRESS PDGF ALPHA-RECEPTORS

Platelet-derived growth factor alpha-receptors (PDGFR alpha) are expre ssed by a subset of neuroepithelial cells in the ventral half of the e mbryonic day 14 (E14) rat spinal cord. The progeny of these cells subs equently proliferate and migrate into the dorsal parts of the cord aft er E16. Here, we show that E14 ventral cells are able to generate olig odendrocytes in culture but that dorsal cells acquire this ability onl y after E16, coinciding with the appearance of PDGFR alpha-immunoreact ive cells in the starting population. PDGFR alpha-positive cells in op tic nerve and spinal cord cultures co-labelled with antibody markers o f oligodendrocyte progenitors. When PDGFR alpha-positive cells were pu rified from embryonic rat spinal cords by immunoselection and cultured in defined medium, they all differentiated into oligodendrocytes. Ver y few oligodendrocytes developed in cultures of embryonic spinal cord cells that had been depleted of PDGFR alpha-expressing cells by antibo dy-mediated complement lysis. These data demonstrate that all PDGFR al pha-positive cells in the embryonic rat spinal cord are oligodendrocyt e progenitors and that most or all early-developing oligodendrocytes a re derived from these ventrally-derived precursors.