Abstract
The inner ear of mammals contains the vestib-ular apparatus which is involved in the maintenance of posture and balance. The tubular structure of the apparatus is bathed by the potassium-rich endolymph and sodium rich perilymph in the luminal and abluminal compartments , respectively. The luminal compartment is lined by a continuous epithelium with islets of receptor organs, which separates the luminal from the abluminal compartment. The present work focuses on the epitheli-um, without the receptor organs, and shows that it can be reconstituted in culture. The epithelium from 4-day-old Wistar rats was grown on microporous membranes. High transepithelial electrical resistances (4000-6000 Ω·cm 2) were achieved after 4-8 days in culture. The epithelium was characterized by the presence of cytokeratin, ZO-1 protein, occludin, and the presence of tight junctions and kinocilia. The transepithelial resistance of the cell mono-layer withstood endolymph/perilymph dual bathing when the apical pole of the cells was in contact with en-dolymph, but collapsed in the reverse configuration. Weak but statistically highly significant basal to apical rubidium (86 Rb) transport was observed. These findings show that this epithelium maintains its in vivo polarity and could enhance the potassium composition of endo-lymph up to maturity. This new culture model, in which dual bathing is possible, should enable further in vitro studies of the sensory vestibular epithelia.