EFFECTS OF ENDOLYMPHATIC DUCT OCCLUSION ON THE STRUCTURE AND FUNCTIONOF THE ENDOLYMPHATIC SAC IN THE ADULT GUINEA-PIG

The endolymphatic sac (ELS) has been shown to respond rapidly to sudde n disruptions in fluid balance such as labyrinthectomy or systemic adm inistration of hyperosmolar agents. The present study was designed to determine the ELS response to slower changes in fluid dynamics by occl uding the endolymphatic duct (ELD), thereby interrupting the longitudi nal flow of endolymph to the ELS. Morphologic studies and autoradiogra phic techniques were used to evaluate the effects of ELD obstruction o n the structure and function of the ELS after 48 hours. There were no significant changes in cellular morphology and a slight decrease in th e incorporation of radiolabeled glucose when compared with normal ELS cells. We conclude that it is rapid change in fluid balance that trigg ers the ELS response, which is not seen with disruption of longitudina l flow.