Table 1.

MAPK/ERK activation does not affect myelination during regeneration but does affect nonmyelinated fiber survival and C-fiber organization in Remak bundles

	Controls	MEK1DD mutants	p value (t test)
G-ratio	0.66	0.64	0.501
Myelinated axon/nerve	3435.9	2872.7	0.202
Nonmyelinated axon/nerve	8032.6	6129.2	0.023
Aberrant myelinated axon/nerve	293.9	599.9	0.026
Total axon number/nerve	11762.4	9601.9	0.048
C-fibers/RB	5.4	2.8	0.001

The numbers of nonmyelinated fibers and total axons are decreased in mutant mice, whereas no significant differences between the two groups are observed for the numbers of myelinated fibers. Aberrant myelinated fibers (presenting with recurrent loops, outfoldings, and myelin decompaction) are increased in mutants. The number of C-fibers/Remak bundles (RBs) shows a dramatic decrease following MAPK activation due to a lack of normal Remak bundle formation. The axon count was normalized for the total nerve area calculated in semithin sections of the same sciatic nerve. n = 3–4 mice/group. Numbers in italics indicate a significant difference between the two groups; two-tailed unpaired t test.