THE COMPARATIVE ANATOMY OF THE PIG MIDDLE-EAR CAVITY - A MODEL FOR MIDDLE-EAR INFLAMMATION IN THE HUMAN

This study was undertaken to develop a functional model of otitis medi a with effusion (OME) in the pig (Sus scrofa), with the purpose of inv estigating the origin of lymphocytes populating the middle ear during the course of an inflammatory process. The relevance of the model to t he human condition of OME is to a large extent dependent on the anatom ical and physiological similarities between the middle ear cavity and the pharyngeal lymphoid tissue of the pig and man. Anatomical specimen s were collected from 7 young Large White pigs to determine the gross anatomy of the middle ear cavity and the histological characteristics of the middle ear mucosa. It was found that the anatomy of the 3 parts of the middle ear cavity in man and in the pig is broadly similar, al though some minor differences were observed. The porcine eustachian tu be was seen to be cartilaginous throughout its length in contrast to t he part osseous, part cartilaginous structure found in man; the porcin e ossicles were slightly different in shape to those of man and the ai r cell system was situated inferior to the tympanic cavity in the pig as opposed to posteriorly in man. This paper describes the structure a nd morphology of the pig middle ear cavity and compares and contrasts it with that of man. The minor differences observed are of anatomical importance but do not diminish the usefulness of the pig middle ear cl eft as a potential model for human middle ear disorders.