Description:
<jats:p>Morphological changes of the middle ear were investigated by means of microotoscopy and scanning electron microscopy in 40 developing Albino rats. In 20 one nostril (group B) and in 20 both nostrils (group C) had been experimentally obstructed. 20 rats were used as controls (group A). Microotoscopy and scanning electron microscopy on the middle ear mucosa were performed when the animals were 2 months old, i.e. at 90% of their development. At microotoscopy the tympanic membranes, homolateral to the obstructed nostril, proved to be abnormal in 81% of group B rats and in almost all rats belonging to group C. Scanning electron microscopy, performed after the bullae had been removed, showed the following epithelial surface changes of the middle ear homolaterally to the obstructed nostril: (a) a significant increase of nonciliated elements with a secretory behavior as compared to controls, even of the floor where normally a large number of ciliated cells is present; (b) several ciliated cells were destroyed and their cilia were irregular and untidy; (c) thick mucous secretions covered the floor of the tympanic bulla; and (d) squamous metaplasia of the hypotympanic epithelium. Extrarotation of the eustachian tubes and developmental abnormalities of the skull base in growing rats, caused by nasal obstruction, seem to be able to induce pathological events of the middle ear.</jats:p>