Ultrastructural features of human Reissner's membrane were investigate
d in two groups of similarly aged patients. Five patients had age-rela
ted normal hearing (ARNH) and four patients had acquired sensorineural
hearing loss (SNHL) from causes other than age. The membrane consiste
d of a mesothelium facing the perilymph and an epithelium facing the e
ndolymph. The two cell layers were separated by a basement membrane. T
he mesothelium was formed by wide spread thin cells with a smooth surf
ace. The epithelial cells assumed two different shapes, flat and round
ed. 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 l
ower 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 patien
ts with SNHL, some flat cells had relatively few long microvilli. The
epithelium showed more pronounced cellular changes in patients with SN
HL than in those with ARNH and these alterations are discussed in rela
tion to sensorineural degeneration.