Figure 4.

Variable optic nerve damage in APP/PS1 transgenic (TG) mice is exacerbated by exposure to blast. Qualitative analyses of nerve damage in paraphenylenediamine (PPD)-stained histologic cross sections of optic nerve from TG-Sham and TG-Blast mice. Representative light microscopy images of optic nerve at (A–C) low (10× objective, 100× total magnification) and (D–F) high magnification (100× objective, 1000× total magnification). There is a decrease in the density of myelinated axons in nerves from TG-Sham compared to Non-TG-Sham mice (E versus D) and TG-Blast compared to TG-Sham mice (F versus E). Also note the increased prevalence of damaged axons (PPD stains the myelin sheath of intact axons and the axoplasm of damaged axons) in TG-Blast compared to TG-Sham mice (F versus E) and TG-Blast compared to Non-TG-Sham mice (F versus D). Scale bars: 100 μm (A–C) and 5 μm (D–F). (G) Stacked bar graph showing the percentage of optic nerves with the indicated damage grade for each cohort of mice using an established qualitative damage grading scale, whereby increasing values represent increasing damage severity (1 = no to mild damage [white], 2 = moderate [gray], 3 = severe [black]). Each bar represents the percentage of nerves with each damage grade for each cohort of mice: Non-TG-Sham (n = 6 mice), TG-Sham (n = 6), and TG-Blast (n = 5). Statistical significance was assessed using a nonparametric Mann-Whitney test. Asterisk represents a P < 0.05.