Inability of regenerating mouse motor axons to innervate a denervated target

We used the triangularis sterni muscle of the adult mouse to study the influence of the connective sheaths that surround a nerve on the regeneration of its crushed axons. Our data indicate that regenerating axons: invade all the branches of a denervated pathway, independent of the presence of endplates; but are unable to escape from the perineurium even when vacant endplate sites are present in the immediate vicinity. Although regenerating axons do not share the first feature with intact sprouting axons, the second feature is common to both.