Responses of mechanoreceptors and thermoreceptors in skin of the snout of the echidna Tachyglossus aculeatus

Abstract

In echidnas anaesthetized with Chloralose, recordings were made, by electrophysiological means, of activity in filaments of nerve supplying receptors in the skin of the snout. In four animals, responses were recorded from a total of 33 receptors of which 29 were studied in detail. These included 14 slowly adapting mechanoreceptors with regular discharge, four slowly adapting receptors with irregular discharge and six rapidly adapting mechanoreceptors. Two of the rapidly adapting receptors were highly vibration-sensitive for stimulating frequencies up to 500 Hz. Responses were also recorded from both warm and cold thermoreceptors. All of the response patterns encountered in echidna skin are similar to those found in other mammals and the only striking difference is that, as in reptiles, thermoreceptors are served by myelinated axons.