Figure 2.

Injury-induced cell proliferation and GFP expression. a, Graph showing the average number of BrdU⁺ cells per lesion at 24 h intervals after injury. Four lesions (1–5 dpi) or two lesions (6–7 dpi) were counted to obtain averages. The increase in proliferation in the INL at 2 dpi precedes the increase in proliferation in the ONL at 3 dpi. At 4 dpi, there are ∼850 cells per lesion in the INL that are labeled by BrdU uptake. By 7 dpi, cell proliferation returns to near baseline levels. b, Graph showing the percentage of BrdU⁺ cells quantified in a that are also GFP⁺ at each day after injury. c–k, Images of BrdU⁺/GFP⁺ cells from 2–5 dpi. c, d, At 1 dpi, few cells were BrdU⁺, although rare cells considered to be rod progenitors (c) and microglia (d) based on their position within the retina could be identified. Rarely, a GFP⁺ proliferating cell in the INL could be found (e–g). h, At 2 dpi, a robust induction of GFP in Müller-like cells was observed, which correlates with the rise in the number of BrdU⁺ cells in the INL at 2 dpi. BrdU⁺ putative microglia were also present (gray arrow). i, At 3 dpi, more BrdU⁺/GFP⁺ cells were observed in the INL. j, At 4 dpi, putative rod progenitors in the ONL can be identified as BrdU⁺/GFP⁻ cells (gray arrow) and BrdU⁺/GFP⁺ cells are abundant (white arrow). In addition, we identified some nuclei that were GFP⁺/BrdU⁻ (arrowhead). k, At 5 dpi, the number of BrdU⁺ cells in the INL is decreasing, but GFP⁺ proliferative cells can be identified in all three nuclear layers (arrows). ♦, ONL; ▪, INL; ▴, GCL.