Tail regeneration in the plethodontid salamander, Plethodon cinereus: induced autotomy versus surgical amputation.

Regeneration of the tail in the plethodontid salamander, Plethodon cinereus, occurs following either surgical amputation or induced autotomy. Autotomy may occur along any one of the caudal myosepta which form natural cleavage planes. The distally attached myofibers break away from the myoseptum which then becomes part of the stump surface remaining intact during subsequent regeneration of the distal segments. Under these conditions, therefore, muscle fibers do not normally participate in tail regeneration. If, however, the myofibers of a caudal myotome are interrupted as in mid-segment amputation, the damaged fibers undergo hyaline degeneration and are largely replaced by connective tissue often as far proximally as the next myoseptum. Other tissues at the amputation surface are concurrently engaged in the epimorphic regeneration of the tail, including myogenesis, though at a slower initial rate than that following autotomy. Muscle cells, therefore, appear not to participate in epimorphic tail regeneration in Plethodon cinereus following either surgical amputation or induced autotomy.