Figure 7.

Axons from surviving RGCs track to discrete regions in the glial lamina, and many other axons that survive in the eye are lost in the lamina. Proving a direct relationship between the pattern of RGC survival/loss in defined regions of the optic nerve and retina, D2.Thy1-CFP–labeled axons were found to run from RGCs surviving in individual fan-shaped regions of the retina to individual local regions in the glial lamina. Mounted tissue was optically sectioned with a confocal microscope, starting at the retinal surface and capturing images at 0.5-μm intervals from the nerve fiber layer through to the glial lamina. (A) Compressed Z stack of a retina and its optic nerve. The pseudo-colored (green, yellow, blue and red) axons on the right side travel from fan-shaped regions in the retina to discrete regions in the glial lamina. The surviving axons on the left (pseudocolored in white) travel from the retina but end just in front of the lamina, clearly showing that some axons that survive in the eye are lost in the lamina. (B) Schematic indicating positions of optical sections shown in other panels. (C and F) Compressed Z stack with outline of the optic nerve at the glial lamina denoted with a dotted ring (C, pseudo-colored; F, raw grayscale). (D and G) Single layer image within the nerve fiber layer. (E and H) Single layer image within the glial lamina with the nerve outlined by the dotted ring. The dotted line indicates the blood vessels entering the optic nerve at this level. Bars, 100 μm.