Fig. 2.

Regeneration of macular cells. Retinal pigment epithelium (RPE) cells in the normal macula are dormant and do not proliferate due to spatial constraints. Degenerated or dead RPE cells from the macula can be replaced by RPE cells from the periphery of the retina where they are more relaxed and can proliferate. RPE stem cells (RPESCs) can self-renew in vitro upon activation and it is hypothesized that they could do so in vivo. If the cells are exposed to stress, they may not be able to proliferate as they may be senescent. SIPS - stress-induced premature senescence