TOPOGRAPHY OF UNMYELINATED AXONS IN REGENERATED SOLEUS NERVES OF THE RAT

The topography of unmyelinated axons on cross sections of normal and regenerated soleus nerves of rat was studied by electron microscopy. The experimental nerves were crushed and assessed after 1-19 weeks. Unmyelinated axons in normal nerves were arranged in few groups. Nerve crush did not alter the arrangement of unmyelinated axons in the proximal nerve. Distal to the crush lesion, however, the unmyelinated axons became scattered throughout the entire cross section. The grouping of unmyelinated axons within the cross section was quantitated by means of a "clustering factor", defined as the percentage of unmyelinated axons in those 10% of the cross-sectional area which had the highest density of unmyelinated axons. The results indicate that unmyelinated axons during regeneration do not follow their original pathways.