Morphology of the endolymphatic duct and sac in the Mongolian gerbil.

A light microscopical study of the endolymphatic duct and sac of the Mongolian gerbil is presented. This animal model was studied because of its tendency to develop a condition of body fluid imbalance which may represent a hazard to the inner ear fluid environment. Particular stress is laid on the combination of the lack of an extraosseous endolymphatic sac and the presence of elastic tissue in the subepithelial space of the sac. These findings highlight the role of this structure for the regulation of the pressure within the inner ear. Lastly, a secretory process is proposed by which a homogeneous precipitate produced in the lumen of the sac can regulate volume and pressure changes.