ENDOLYMPHATIC AND ASSOCIATED DUCTS IN MAN

Abstract

HISTORICAL REVIEW Although numerous studies have dealt painstakingly with the nervous portions of the membranous labyrinth, few have been concerned with the structure of the non-nervous areas of the epithelial ducts. Consequently, little was known until recently about the endolymphatic duct in man. Two portions of the duct system have of late received attention, namely, the slitlike communication of the endolymphatic duct with the utricle and the rugose wall of the endolymphatic duct itself. In 1928 Bast¹ first described the "cusp or valve" which in the human embryo "projects into the utriculus and guards the utricular opening into the utriculo-endolymphatic duct." Struck by its definiteness, Bast expressed the belief that so pronounced a structure must serve a function and suggested that "in case of any sudden pressure disturbance this valve may prevent the outflow of endolymph from the utricle, thus maintaining a more constant pressure within the