STRUCTURE AND ORIGIN OF MIDDLE-EAR CORPUSCLES

The incidence, origin, structure and composition of middle ear corpusc les (MEC) were studied by dissection microscopy, by special stains and immunocytochemistry of histological sections and by transmission elec tron microscopy. MEC are formed within fibrous bands derived from tran sparent fibrous sheets which appear mainly in the mastoid antrum in th e middle-aged and elderly. MEC are covered by a layer of epithelial ce lls with a normal basal lamina, and are largely composed of concentric layers of collagen which display alternating positive and negative bi refringence. Pulmonary and prostatic corpora amylacea show a similar l ight microscopical structure and age relationship, but contain amyloid . It is suggested that MEC and the other bodies may be organized foci of epithelial basement membrane expansion perhaps derived from an in v ivo counterpart of the 'domes' seen in vitro in some monolayer epithel ial cultures.