Ossicular and otic capsular lesions in LP/J mice.

Otosclerosis is an inherited disease in which abnormal bone growth results in ossicular fixation and hearing loss. Although the disease affects up to 10% of humans, it has not been observed in other animals. The LP/J inbred mouse has been found to develop abnormal bony lesions of the middle ear which resemble human otosclerosis. In this study of 113 temporal bones from LP/J mice, we found that the lesions develop after puberty and involve only the ossicles and the otic capsule. The most frequent site of involvement was the incus (46.9%), followed by the anterior crus of the stapes (31.3%), the malleus (14.2%), the otic capsule (14.2%), and the stapes footplate (8%). Cochlear hair cell loss was progressive throughout the lifespan of these animals. Although this disease is not identical in histologic appearance to human otosclerosis, understanding its disease process may shed light upon the pathophysiology of the human disease.