Nano-gold TEM visualization of FIZ1's subcellular distribution in the P-35 mouse neural retina. A) Light micrograph (400X) of the adult mouse neural retina, illustrating the relative layers and their location: the Ganglion Cell Layer (GCL), whose neurons form the optic nerve; the Inner Nuclear Layer (INL), nuclei of bipolar, horizontal and amacrine cells; the Outer Nuclear Layer (ONL), containing photoreceptor nuclei; the photoreceptor Inner Segments (IS); and the photoreceptor Outer Segments (OS), the location of disk membranes and phototransduction proteins, including Rhodopsin. (Lowicryl embedded section, Toluidine blue stain.) A) and B) Rod nuclei display dense chromatin staining throughout most of their nuclear volume (arrowhead). Cones have dense chromatin staining in a much smaller proportion of their nuclear volume (arrow). C) Nano-gold labeling of FIZ1 in the central ONL (arrowhead). Rod photoreceptors dominate. D) FIZ1 labeling in rod (arrowhead) and cone (arrow) nuclei near the ONL/IS boundary. E) ONL, pre-adsorbed antigen control. F) FIZ1 labeling of the photoreceptor IS region. The outer limiting membrane at the ONL/IS interface is indicated (arrow). G) IS, pre-adsorbed antigen control. H) The OS region did not display label for FIZ1. Pigment granules from the Retinal Pigment Epithelium (RPE) are present (arrow). I) FIZ1 labeling of the GCL, nuclei are positive for FIZ1 (arrowhead). J) GCL, pre-adsorbed antigen control. K) The INL layer, nuclei are positive for FIZ1 (arrowhead). L) INL, pre-adsorbed antigen control.