Figure 4: The retina in a normal SD rat older than 50 weeks. The brown region shows stained GFAP. A: optic nerve disc; B: ILM; C: INL; D: outer nuclear layer; E: retinal pigment epithelium; F: index of 100 μm. The area of stained GFAP is limited around the ILM and does not appear around the INL.