The mucosal lining of the Eustachian tube of the rat.

This report deals with a microscopical study on the Eustachian tube of the rat. The tube consists of a small membranous part and a larger part which is supported by cartilage to a varying extent. The epithelial lining is composed of pseudostratified ciliated epithelium and squamous epithelium, both arranged in coherent fields, extending from nasopharynx to the middle ear cavity. The ciliated epithelium, which is continuous with the tracts of ciliated epithelium in the middle ear, provides morphological evidence for the existence of a mucociliary transport system. The part of the tube, that is lined by squamous epithelium is suggested to be involved in facilitating the passage of air. The observations made on the secretory elements refer to a different function of goblet cells and the subepithelial compound glands in Eustachian tube physiology.