Microglia mediate the cytotoxic effects of TNF-α. A, CD11b immunostaining in optic nerve sections at the indicated times after intravitreal injections of TNF-α or PBS. Scale bar, 100 μm. B, Quantitation of CD11b⁺ microglia in optic nerves. **p < 0.01 as compared with PBS-treated controls at the same time points (n = 8 per time point). C–F, APC⁺ oligodendrocytes in optic nerves of Mac-1^−/− mice exposed to intravitreal injections of TNF-α (TNF-α, i.v.), direct application of TNF-α from a Spongel wrapped around the optic nerve (TNF-α on), or increased IOP (OH). Scale bar, 50 μm. G, Quantitation of APC⁺ oligodendrocytes 14 d after treatment. H, DiI-labeled RGCs in flat-mounted retinas of wild-type mice or Mac-1^−/− mice 4 weeks after increasing IOP. Scale bar, 100 μm.