Figure 6. Apoptosis assay: optic nerve, after crush and rAION. A: Normal optic nerve; no apoptotic cells are detected. B: Positive control. C: TUNEL-positive (red) cells along the optic nerve 3 days following crush injury of wild type mice. D: TUNEL staining of optic nerve of GFP-CNPase mice 3 days following crush showing positive staining. Oligodendrocytes apoptotic cells are yellow (green for GFP and red represent positive staining for apoptosis), suggesting that oligodendrocytes in the optic nerve proximal to the globe undergo apoptosis 3 days following induction of crush injury. E: The whole optic nerve of same GFP-CNPase mice (D) is shown. F: Optic nerve head, 3 days following crush injury; showing hemorrhage (asterisk), immediately posterior to the globe. G: Same damaged area at higher magnification, demonstrating loss of oligodendrocytes and focal hemorrhagic area. H: Optic nerve head 3 days following rAION induction, showing preserved architecture of retina and intraocular optic nerve, without apoptotic cells. I: Same nerve as H, 3 days after rAION, demonstrating the anterior segment of the optic nerve behind the globe. Note few TUNEL-positive cells (red staining, arrows) at the center of the anterior optic nerve.