Axonal degeneration in the spinal cord of Irp2-null mice.

A; Toluidine blue staining of Epon-embedded spinal cord cross-sections at 12 months. Red-circled areas indicate where myelin dense body (MDBs) were found. The yellow star represents the area enlarged in Figure 1B. Scale bar = 200 µm. B; Ventral white matter (L4) from wildtype (a), Irp1^+/+;Irp2^-/- (b), Irp1^+/-;Irp2^-/- (c) mice at 12 months. Arrows indicate MDBs. Scale bars = 50 µm, 20 µm (inset). C; Quantification of MDBs per spinal cord sections at 4, 7.5, 12 months. The bar chart show average±SEM, n = 4-5, **; p<0.001, analyzed by two-way ANOVA. A summary of the pairwise comparisons is presented in Table S1. D; Progressive accumulation of MDBs in ventral white matter of spinal cords at 4, 7.5 months. Scale bars = 10 µm.