Figure 8. Neurogenesis in the pars plana in mice with MNU-induced photoreceptor degeneration. Double-headed arrows indicate the pars plana. MNU was injected at P30 and BrdU (50 mg/kg) was injected at P32. A, B, F: At P37, increased numbers of BrdU-positive cells were observed in the pars plana of MNU-treated mice (A) compared to untreated controls (B), which is summarized in F. Note that BrdU-positive cells in a linear alignment in the retina of B were blood cells in retinal vessels. C: Representative image of a cell positive for both recoverin and BrdU (arrowhead) in the peripheral retina at P40. D,H: Proportions of cells positive for PNA (cone) or rhodopsin (Rho; rod) among recoverin-positive cells in the pars plana (H) are presented. Note that the abrupt alteration in the cone-rod ratio signified the cilioretinal border. E, I: Rare cells positive for both recoverin and BrdU were identified in the pars plana of MNU-treated mice (E; n=8); such cells were never observed in control mice (I; n=12). G: At P37, increased numbers of recoverin-positive cells were observed in the pars plana of MNU-treated mice (n=8) as compared to the controls (n=12). For H, after the number of recoverin-positive cells within 320 µm width of the pars plan were determined from a single optical scan (10.0 μm thick), the number of those also positive for rhodopsin and PNA were determined from the same image. Three independent images randomly obtained from the same eye were analyzed to calculate the proportion of recoverin-positive cells that were also positive for rhodopsin (Rho) or PNA (PNA) or neither (Rcv) per animal. Average proportion (%; mean±SEM) of cells for each of the three categories were determined from 8 animals. For F, G, and I, the number of cells positive for BrdU, recoverin, or both within 320 µm width of the pars plana were determined from an optical scan (10.0 μm thick). Values from three independent images randomly obtained from a same eye were averaged. Data extracted from totals of 8 MNU-treated mice and 12 control mice were statistically processed and were presented as means±SEM A and B are thick scans merged from 2 scans (each scan was 10.0 μm thick) while C is presented as a thin scan (a single scan 3.9 μm thick). D and E are also thick scans but merged from 3 scans (each scan was 10.0 μm thick). Scale bar equals 25 μm in C-E and 50 μm in A and B. Abbreviation: recoverin (Rcv).