Ultrastructural features of human Reissner's membrane

Ultrastructural features of human Reissner's membrane were investigated in two groups of similarly aged patients. Five patients had age-related normal hearing (ARNH) and four patients had acquired sensorineural hearing loss (SNHL) from causes other than age. The membrane consisted of a mesothelium facing the perilymph and an epithelium facing the endolymph. The two cell layers were separated by a basement membrane. The mesothelium was formed by wide spread thin cells with a smooth surface. The epithelial cells assumed two different shapes, flat and rounded. Both epithelial cell types were covered with many short microvilli. In all specimens, the rounded cells were arranged in bands, strands, whorls and clusters. The size of bands and whorls was larger in the lower half of the basal turn and decreased gradually towards the apex. Bands and whorls were both larger in specimens from patients with SNHL than in those with ARNH and expanded up to the middle turn. In patients with SNHL, some flat cells had relatively few long microvilli. The epithelium showed more pronounced cellular changes in patients with SNHL than in those with ARNH and these alterations are discussed in relation to sensorineural degeneration.