Conduction of nervous impulses in spinal roots and peripheral nerves of dystrophic mice

Abstract

Conduction was studied in the sacral ventral roots and ventral tail nerves of dystrophic mice ( dy/dy) and phenotypically normal littermates. In myelinated ventral root fibers of normal mice, conduction velocity was uniform with internodal conduction time45 ± 5 μsec (26 °C). In ventral root fibers of dystrophic mice, conduction velocity was decreased and strikingly non-uniform; both saltatory and continuous conduction were observed in different portions of the same nerve fiber. Continuous conduction with velocity <2 m/sec (26 °C) was characteristically observed in mid-root where the axons are bare; conduction was saltatory close to the exit from the spinal canal and near the spinal cord where the axons are myelinated. Maximum conduction velocity in ventral tail nerves was21 ± 3 m/sec for dystrophic mice and31 ± 4 m/sec for littermate controls (37 °C). Internodal lengths were somewhat decreased in the dystrophic peripheral nerves but there was no significant difference in maximum fiber diameters, myelin thickness or nodal morphology between dystrophic and normal nerves.