FIG. 4.

Several potential sources of endogenous regeneration exist within the mammalian retina. Neurons could be produced from cells in the retinal pigment epithelium (green) or lingering progenitors in the ciliary marginal zone (orange), as in other vertebrates. Current protocols can provoke neurogenesis from Müller glia (yellow). Existing mature neurons could potentially acquire functions of closely related neuron types, such as amacrine cells (blue) for RGCs, or bipolar cells (purple) for rods.