(A and B) Representative electron micrographs of axon cross sections in the P60 euploid control (A) and Ts65Dn (B) corpus callosum. Scale bar = 1 μm.
(C) Graph of the numbers of myelinated axons in euploid versus Ts65Dn revealing a trend towards a decrease in the number of myelinated axons in Ts65Dn mice.
(D) Histogram indicating a decrease in the proportion of small diameter axons and an increase in the proportion of large diameter axons (>1 μm) in Ts65Dn mice. *, p≤0.05; #, p=0.058 (paired t-test).
(E) Plot of g-ratios (y-axis) and the corresponding diameter for all axons assessed. Black dots = euploid control; red dots = Ts65Dn.
(F) Bar graph showing there is a significant increase in the mean g-ratio in Ts65Dn mice indicating thinner myelin sheaths around Ts65Dn axons. *, p=0.011 (paired t-test).
(G) Histogram indicating that the g-ratios of small diameter, but not large diameter axons, are higher in Ts65Dn mice. #, p≤0.08 (paired t-test).