Experimental study of the regenerative potential of perineurium at a site of nerve transection.

A single fascicle of sciatic nerve was transected in a series of rats. The nerve was repaired by one of three experimental models: 1) perineurial suturing with bulging axons untrimmed. 2) perineurial suturing with bulging axons trimmed, and 3) perineurial suturing to produce a misaligned fascicle. Nerves were excised at 0 to 42 days and were examined in thin, longitudinal section. The complete absence of perineurial regeneration was observed at all time intervals and in all models. Regeneration of axons within the fascicle was disordered. Axonal regeneration extended into the surrounding connective tissue and infiltrated both the proximal and distal perineurium.