Figure 2

Figure 2

Ultrastructural Analyses of the nfascb^ue56 Mutant Spinal Cord

(A and B) Transmission electron microscopy (TEM) images of sections through the spinal cord of wildtype (A) and nfascb^ue56 mutants (B) at 5 dpf. Dorsal to the top, midline left. Asterisks show myelinated cell bodies. Scale bars, 5 μm.

(C–D′) TEM images of cell bodies in wildtype (C and C′) and ue56 mutants (D and D′) showing enwrapment of a cell body in the mutant with multi-lammellar myelin. Scale bars, 1 μm.

(E–H) High magnification views of myelinated axons in the dorsal (E and F) and ventral (G and H) spinal cord of wildtype (E) and mutant (F) animals. Unmyelinated axons with a diameter >0.3 μm highlighted in blue. Scale bars, 0.5 μm.

(I) Number of axons with a diameter > 0.3 μm in wildtype and nfascb^ue56 mutants (wildtype mean 114.5 ± 23.71 SD, n = 6 animals, nfascb^ue56 mutant mean 111.4 ± 23.69 SD, n = 7 animals, p = 0.8201, t test).

(J) Total number of myelinated axons in wildtype and nfascb^ue56 mutants, and numbers in the dorsal and ventral domains of the spinal cord. (Total: wildtype mean 92.17 ± 19.57 SD and nfascb^ue56 mutant mean 53.57 ± 18.20 SD, p = 0.0036, t test. Dorsal: wildtype mean 36.17 ± 7.89 SD and nfascb^ue56 mutant mean 21.93 ± 8.60 SD, p = 0.0103, t test. Ventral: wildtype mean 56.00 ± 12.52 SD and nfascb^ue56 mutant mean 31.64 ± 11.81 SD, p = 0.0041, t test. All sets wildtype n = 6 animals and nfascb^ue56 mutant n = 7 animals).

(K) Average g-ratio per animal in wildtype and nfascb^ue56 mutants at 5 dpf (wildtype mean 0.72 ± 0.01 SEM, n = 6 animals and nfascb^ue56 mutant mean 0.73 ± 0.01 SEM, n = 7 animals, p = 0.7027, t test).

(L) G-ratios of all myelinated axons assessed in the dorsal spinal cord of wildtype (black) and nfascb^ue56 mutants (red) relative to axon caliber. Each point represents a myelinated axon.