Fig. 3. Late degeneration of the Fz5^-/- retina. (A,B) Semi-thin, plastic-embedded sections of (A) WT and (B) Fz5^-/- mouse retinas at 6 months of age stained with Toluidine Blue. In the Fz5^-/- retina, there is a nearly complete loss of photoreceptor outer segments (OS), swelling of inner segments (IS), and cell and neuropil loss in the two plexiform and three nuclear layers (ONL, outer nuclear layer; INL, inner nuclear layer; GCL, ganglion cell layer). (C) Fz5^-/- retina and choroid at 6 months of age showing extensive retinal folding and detachment. (D,F) High-magnification views from C, showing detachment and folding (D) and rosette formation (F). (E) High-magnification view of the upper right corner of D showing that the subretinal space is populated by macrophages (arrowheads).