Autonomic Nervous System of the Cat Middle Ear Mucosa

Abstract

The autonomic nerves of the cat middle ear mucosa were studied by the methods of surface preparation, histochemistry and electron microscopy. The tympanic nerve was found to contain large myelinated fibers probably of a sensory nature. Other sympathetic bundles consisted primarily of unmyelinated fibers with a sparse distribution of myelinated fibers. The inferior tympanic artery was accompanied by many vasomotor nerves and its branches were also innervated predominantly by adrenergic fibers. A dense neural network which showed acetylcholinesterase activity was found in the mucosa around the Eustachian tube orifice. These nerves consisted of several unmyelinated fibers encapsulated by a single Schwann cell just below the epithelium. The fine structure of the small ganglions of the tympanic plexus revealed that the cholinergic nerve endings synapse with the cell body of the ganglion. This finding suggests that these ganglions are autonomic.