Figure 7

Tsk mouse optic neuropathy. (a) Optic nerve cross-sectional area was greater (*p = 0.01) in Tsk (n = 24) compared with WT mice (n = 22). (b) Analysis of axon density in optic nerve regions showed this was significantly lower (*p = 0.02, ♯p = 0.06; scale bar, 20 µm) superotemporally and possibly temporally. S = superior; T = temporal; I = inferior; N = nasal. White bar: WT (n = 8); red bar: Tsk (n = 8). (c) Axon counts cumulative of all optic nerve sectors showed no difference (p = 0.98) between WT (n = 10) and Tsk mice (n = 8), masking specific regional differences seen in (b). (d) Looser packing and trend toward larger axons in the superotemporal region of Tsk (bottom) compared with WT (top) mouse optic nerves (both aged 11–14 m; paraphenylenediamine staining; magnification × 100; scale bar, 10 µm). (e) Glial activity in optic nerve seen in cross-section views (red, GFAP-`positive; scale bar, 20 µm) comparing Tsk and WT mice. (f) Altered organization of optic nerve axon myelin sheaths, neurofilaments (open arrows) and astrocyte processes (arrowheads; scale bar, 0.5 µm) of Tsk but not WT optic nerves in representative transmission electron microscopy. Error bars: standard error of mean; except 3A shows 2.5th to 97.5th centiles with median.