EXOGENOUS GLYCOSAMINOGLYCANS INDUCE COMPLETE INVERSION OF RETINAL GANGLION-CELL BODIES AND THEIR AXONS WITHIN THE RETINAL NEUROEPITHELIUM

Prior to forming an axon, retinal ganglion cells retain a primitive radial configuration while maintaining ventricular and vitreal endfeet attachments. During their subsequent differentiation, ganglion cells polarize their cell body and axon only along the vitreal surface. When the ventricular surfaces of intact retinas in organ culture were exposed to free chondroitin sulfate (CS) in solution, both the cell body and nerve fiber layers were repolarized to the opposite side of the neuroepithelium. However, the basal lamina remained in its usual position. Thus, the ability to initiate an axon is not restricted to the vitreal endfoot region of differentiating neurons, and in addition, the radial position at which the axon emerges can be mediated by the location and concentration of the extracellular CS milieu.