## 3 Results
### Distribution of Myo/Nog Cells Shift in Number and Location with Stress  
The spatial distribution of Myo/Nog cells also changed dynamically, with increasing numbers detected in the ONL and choroid over time, particularly in areas with the highest levels of TUNEL+ apoptotic photoreceptors (Figures 3-6).  
The quantification of Myo/Nog cells revealed a statistically significant increase in their numbers at week 3 compared to week 2.5 (\(p<\) 0.05), indicating a rapid response to early-stage photoreceptor degeneration (Figure 4). By week 5, Myo/Nog cells were highly concentrated in the ONL, with the highest densities in regions adjacent to apoptotic photoreceptors. This distribution suggests that Myo/Nog cells migrate toward sites of photoreceptor loss and may contribute to apoptotic cell clearance (Figures 4-6).  
Figure 2: **Comparison of C57 and C3H retinal layers at week 2.5 and week 6.** Eye sections from the mid-periphery of each animal’s retina, stained with H&E, show the retinal layers, as indicated by the text above. Significantly reduced OPL and ONL can be seen in the C3H sections (**right**) when compared to their C57 counterparts (**left**).  
Figure 1: **Difference in ONL/INL ratios between C57 and C3H mice from postnatal week 2.5 to postnatal week 6.** The ONL/INL ratio was calculated by measuring the depth of each layer in fields surrounding the optic nerve and dividing the ONL by the INL. This ratio was significantly larger for C57 mice than the C3H mice for each time point measured along the retina. The difference between the C57 and C3H ONL/INL ratio increased as time progressed from week 2.5 to week 6. The C3H mice showed a significant decrease in ONL/INL ratios between weeks 2.5 and 3, as well as between weeks 3 and 4 (\(p<0.05\)). A significant difference was found for ONL/INL ratios of all C3H time point groups compared to their C57 counterparts at each retinal location (* indicates \(p\leq 0.05\)).  
Additionally, comparisons with C57 mice showed that Myo/Nog cells in healthy retinas remained relatively stable in their numbers and localization, reinforcing the notion that their proliferation and redistribution in C3H mice are driven by retinal degeneration (Figures 3-6).  
Localization of Nuclear Remnants Inside Myo/Nog Cells Capable of Phagocytosis of Degenerating Photoreceptors  
As the resident immune cells of the retina, microglia are highly responsive to injury or stress. In retinal degeneration, they migrate to areas of cell death, including the ONL, as well as phagocytose apoptotic cells and debris. Microglia are considered professional phagocytes and are essential for maintaining retinal homeostasis and preventing secondary inflammation. Myo/Nog cells were previously shown to be phagocytic in the skin and anterior segment of the eye [15]. Though typically less numerous than microglia, Myo/Nog cells may also play a supportive role in clearing debris if they migrate to the ONL during stress. Sections of C3H mice were double-labeled with the BAII mAb and TUNEL reagents to examine whether Myo/Nog cells might be involved in clearing degenerating photoreceptors.  
Figure 3: **Number of Myo/Nog cells in the retinas of C57 and C3H mice.** Total Myo/Nog cells in all retinal layers were counted and averaged for each time point. Myo/Nog cells were significantly more numerous at all time points in C3H mice compared to C57 mice (* indicates \(p\leq 0.05\)).  
Figure 4: **Distribution of Myo/Nog cells throughout the retinal layers at different time points of C57 and C3H mice.****(A,C,E,G,I)** represent C57 mice in which the majority of Myo/Nog cells are in the INL-OPL layers of the retina. (**B,D,F,H,J**) represent C3H mice with the majority of Myo/Nog cells in the ONL and choroid. There was no statistical difference between the distribution of Myo/Nog cells in the GCL between the C3H and C57 mice. The distributions of Myo/Nog cells found in the choroid-ONL and INL-OPL layers of the retina were statistically different in C3H mice compared to C57 mice (* indicates \(p\leq 0.05\)).