Figure 1. Caspr labeling in rat and mouse retina. A: Photomicrograph of monoclonal Caspr labeling in rat retina. Arrow indicates one of several retinal ganglion cells (RGCs) intensely labeled by Caspr. In addition to RGCs, somas of many amacrine cells in the inner nuclear layer (inl) were also labeled (e.g., arrowheads). The inner plexiform layer (ipl) was diffusely labeled while the outer plexiform layer (opl) contained several hot spots. B: Lower power photomicrograph of Caspr labeling in rat retina using a rabbit polyclonal antibody. A nearly identical pattern of labeling was observed as in A. C: Single confocal section of rat retinal wholemount labeled with a monoclonal Caspr antibody. Intense labeling of axon fiber bundles was observed (arrowheads) as well as somas of nearly all cells in the ganglion cell layer. Both large RGCs (asterisk) and likely displaced amacrine cells (arrow, somas <10 μm) were labeled. D: Photomicrograph of Caspr labeling in the rat optic nerve. Inset shows magnified view of node indicated. Arrow indicates another labeled node. E: Photomicrograph of Caspr labeling (mAb) in mouse retina. Similar to the rat retina (A, B) intense labeling of RGCs and fiber bundles were observed as well as many amacrine cells in the inl. F: Photomicrograph of Caspr labeling (mAb) in knockout retina. All labeling of retinal cell types was eliminated, leaving only nonspecific labeling of retinal blood vessels. Scale bars equal to 25 μm.