Otosclerosis. Histopathology, light and electron microscopy.

Cochlear otosclerosis, in the histopathological sense, is not uncommon but remains a clinical enigma. Similarly the aetiology of otospongiosis has remained obscure. Nevertheless the enzymatic concept of the initiation and mechanism of the underlying process has been recognized and confirmed together with the essential function of the matrix vesicles forming the site of primary enzymatic calcification. It may be concluded that otospongiosis is a primary lytic process initiated by lysosomal enzymes of matrix vesicles activated in the cartilaginous cell rests of the area. The cause of the process is still unknown.