TRANSPLANTATION OF OLIGODENDROCYTE PROGENITOR CELLS INTO THE RAT RETINA - EXTENSIVE MYELINATION OF RETINAL GANGLION-CELL AXONS

In most mammals, retinal ganglion cell axons are unmyelinated in the r etina. The same axons become myelinated in the optic nerve. Various st udies suggest that retinal ganglion cell axons are also in principle, myelination competent intraretinally and that non-neuronal factors at the retinal end of the optic nerve prevent the migration of oligodendr ocyte progenitor cells into the retina. To test this hypothesis direct ly, we injected oligodendrocyte progenitor cells into the retina of yo ung postnatal rats. We observed massive myelination of ganglion cell a xons in the retina I month after cell transplantation. Electron micros copic analysis revealed that intraretinal segments of ganglion cell ax ons were surrounded by central nervous system myelin sheaths with a no rmal morphology. Our results thus provide direct evidence for the myel ination competence of the intraretinal part of rat retinal ganglion ce ll axons. (C) 1996 Wiley-Liss, Inc.