Chapter 41 The expression of sensory receptors on regenerating and regenerated cutaneous C fibres

Abstract

This chapter focuses on the expression of sensory receptors on regenerating and regenerated cutaneous C fibres. A characteristic of cutaneous C fibre sensory receptors, and probably also of those on C fibres innervating deeper structures, is their propensity to undergo long-term changes in sensitivity to these various stimuli following a variety of perturbations to the nerve or its endings. This can give rise to sensory disturbances, such as the pain consequent on peripheral nerve injury in humans, and those which result in the autotomy seen in many species of animals after peripheral nerve transection. This view of an independent expression of sensory receptor types is evidenced, for example, by the finding that one day after treating a cutaneous nerve with capsaicin there is a selective loss of the mechanoreceptors which are normally present on the same C fibre endings as the thermoreceptors. Clearly much remains to be learnt about the nature of sensory receptors of regenerating C fibres, not only those of cutaneous afferents but also those with muscle and visceral projections.