Adrenergic Innervation in the Rabbit Cochlea

Abstract

The distribution of adrenergic nerve fibres in the rabbit cochlea was investigated with fluorescence and electron microscopic techniques. Interest was focused on the habenula region. After administration of a false transmitter the fine structure of adrenergic nerve fibres and their relationship to other structures were studied. A multitude of adrenergic nerve terminals were found around radiating nerve fibres where they lose their myelin sheaths. Apart from this nerve fibre innervation there was an extensive innervation of the spiral vessel of the tympanic lip, under the inner hair cell. This blood vessel was of capillary size and lacked contractile elements. No adrenergic innervation was observed in the organ of Corti or in the stria vascularis. The cochlear adrenergic innervation was found to have its origin in the ipsilateral superior cervical ganglion. Possible ways of adrenergic influence on sound perception was discussed.