Impaired transport of iron-dextran complex in myelinated central fibers

The labeling of retinal ganglion cells by axonal transport of an iron-dextran complex (injected into the superior colliculus and the lateral geniculate nucleus) was compared to the previously described labeling of the dopaminergic neurons of the substantia nigra (after striatal injection), to test the validity of the method in myelinated and unmyelinated CNS pathways. It was shown that the retrograde labeling in the visual pathway was impaired, consecutive to the penetration of iron-dextran into the myelin sheaths and a subsequent myelin alteration along the optic nerve.