Horseradish Peroxidase in the Lateral Cochlear Wall: An Electron Microscopic Study of Transport

Abstract

Intravenous injection of the enzyme, horseradish peroxidase (HRP), delineated potential physiologic pathways in the lateral cochlear wall of guinea pigs. This tracer passed through the vessel walls in the stria vascularis primarily by vesicular transport and not through endothelial intercellular clefts. Pores formed in stria vessel walls, probably in response to histamine-serotonin release. The vessels of the spiral ligament and prominence were impermeable to this protein. Horseradish peroxidase labeled the intercellular spaces between marginal and intermediate cells, but the basal cells formed a barrier preventing passage into the spiral ligament. Horseradish peroxidase entered the intermediate cells by micropinocytosis. No HRP was seen within marginal or basal cells.