Ultrastructure of the Human Tympanic Membrane

Abstract

In order to arrive at a better understanding of the aetiology and patho-genesis of middle-ear diseases through basic knowledge concerning the electron microscopic appearances in the normal middle ear, a study of the ultrastructure of the human tympanic cavity has been instituted in our Laboratory. The preparations for the present study were fixed from 55 min to 4 hours post mortem Fixation later than 3 hours post mortem resulted in structural autolytic damage. The tympanic membrane consists of three layers: the epidermis whose ultrastructure was found to correspond to the findings in the epidermis of normal skin, the lamina propria containing loose connective tissue, vessels, nerves, and two layers of collagen fibrils (also in the pars flaccida), and the lamina mucosa. In the pars flaccida the mucosal layer consisted of simple squamous cells with microvilli. All through the pars tensa there were cells of varying height, often pseudostratified columnar cells with a large number of cilia and secretory granules. Goblet cells were not found in the normal tympanic membrane, but in large numbers in two cases of chronic otitis media. Under pathological circumstances the faintly secreting, ciliated epithelium of the drum may be converted into a briskly secreting epithelium.