1991 Volume 1991 Issue Supplement41 Pages 146-162
To study the blood-middle ear and blood-inner ear barrier, both vascular and epithelial permeability were examined by light and electron microscopy using the tracer of horseradish peroxidase (HRP) method.
Most of the capillaries of th e middle ear mucosa did not allow HRP to leak, but otitis media increased capillary permeability to HRP. Epithelial cells of the middle ear mucosa took up the tracer from the middle ear cavity, and the degree of uptake of the tracer was enhanced by inflammation in the middle ear. These findings suggest that the blood-middle ear barrier does not play an important role in the middle ear, the latter in which otitis media often clinically occurs. Capillaries i n the vestibular organs and spiral ligament did not show leakage of HRP, suggesting they are of the brain type. However, capillaries of the stria vascularis did show leakage, suggesting they are of the muscle type.
Capillaries of the endolymphatic sac and cochlear plexus were found to be of the fenestrated type. Furthermore, perilymphatic perfusion of HRP showed that the endolymphatic space was sealed by epithelial tight junctions. These findings suggest that the blood-inner ear barrier of the vestibule and spiral ligament consists of both the blood-perilymph barrier and perilymph-endolymph barrier, and that of the stria vascularis consists of only the prilymph-endolymph barrier.
