Mechanoreceptors in rabbit ear skin innervated by myelinated nerve fibres.
1. The activity of single myelinated fibres innervating mechanosensitive units in the dorsal skin of the ears of New Zealand White and Chinchilla rabbits has been recorded with glass micropipette electrodes, inserted into intact bundles of the great auricular nerve.2. Only two types of afferent unit were observed: hair units, sensitive to hair displacement, and skin spot units, sensitive to deformation of spot-like areas of skin between the hair orifices. Hair units were more numerous and no unit contained receptors of both types. Up to nine hairs or six skin spots composed each hair or skin spot unit, respectively. Both types were rapidly adapting.3. The areas of the receptive fields of the hair units were significantly larger in the New Zealand White than in the Chinchilla strain.4. In the hair units from the Chinchilla rabbits: (a) there was no correlation between the receptive field areas and the conduction velocities of the afferent fibres; (b) the areas and conduction velocities of the units showed no significant topographical distribution over the ear; (c) the extent of the overlap of the receptive fields was estimated and the sum of the areas is shown to be about 40 times the area of the ear.