Degeneration and regeneration in crustacean peripheral nerves

Summary

Morphological (Figs. 3–5) and physiological (Fig. 2) data from several crustacean species kept at 19–21 °C show that isolated stumps of motor axons often survive intact for 150–250 days whereas sensory axonal segments usually degenerate within 20 days. Axonal segments of both motor and sensory axons that remain connected to their cell body generally remain functionally and morphologically normal after lesioning. No evidence was found for collateral innervation of denervated muscles from intact motor neurons supplying nearby muscle masses, although the motor nerve terminals may not have completely degenerated. Evidence is presented that motor axons specifically re-innervate their original muscle mass if such re-innervation occurs within 90 days after lesioning. Regenerating sensory and motor fibers make appropriate CNS and peripheral connections so as to re-establish correctly a peripheral reflex (Fig. 2C) found in intact animals (Wilson and Davis, 1965).