Figure 3.
Ultrastructural analysis revealed the presence of synaptophysin-positive vesicles at the ONH after LIOH. ONH tissues harvested 2 d after LIOH were processed for electron microscopy along with control tissues. Antibodies directed against synaptophysin were used in postembedding immunogold labeling. A, Control ONH. Unmyelinated RGC axon fibers (asterisks) are highly organized and in close association with astrocyte processes (As). B, C, LIOH ONH. Axon fibers were disorganized and often displayed swollen regions densely packed with membrane-bound organelles, including mitochondria (M), multilamellar bodies (MLB), translucent vesicles (V), and dense core vesicles (DCV). The translucent vesicles were sometimes scattered among other organelles (B) and sometimes aggregated in close apposition to the axolemma (C). Asterisks indicate neighboring axons that appeared similar to the normal axons in control ONH tissues. D–I, Medium- and high-magnification electron micrographs to visualize immunogold labeling. D, Only sparse gold particle labeling was seen in the control. E, F, Intense labeling over translucent vesicle clusters (arrows) in LIOH. Arrowheads in F point to electron-dense areas in association with the vesicles. G, Vesicles were occasionally observed in control axons (arrow). H, Another example of synaptophysin-positive vesicles (arrows), demonstrating electron-dense regions (arrowheads) along the abutting axolemma. I, Immunogold staining along the axolemma of one axon (arrows). Scale bars: (in C) A–C, 300 nm; (in F) D–F, 200 nm; (in I) G–I, 100 nm.