Reinnervation of distal sensory nerve environments by regenerating sensory axons

This study investigated the specificity of sensory nerve regeneration in a primate model. In adult cynomolgus monkeys, the femoral nerve was explored in the groin and two sensory branches identified. A sensory branch was sectioned and introduced into the proximal channel of a Y-shaped silicone chamber. This proximal sensory nerve stump was given distal choices of distal sensory nerve graft or distal sensory nerve which was intact to the distal sensory cutaneous receptors. After eight months, histological analysis confirmed axonal growth directed towards both the distal nerve graft and the distal nerve intact to the distal cutaneous receptors. However, the number of nerve fibres directed towards the distal nerve was significantly greater than the number of nerve fibres directed towards the nerve graft (P less than 0.004). These results suggest that while both distal nerve graft and distal intact nerve act as specific targets to regenerating proximal primate nerve, the presence of an intact distal end-organ positively enhances sensory regeneration.