Vestibular Dark Cells and Supporting Cells

Abstract

Dark cells are found on either side of the vestibular organs. The dark cell epithelium consists of cells with multiple pinocytotic vesicles close to their luminal surface. A large number of infoldings occur at the basal end of the dark cell toward the basal membrane. These infoldings contain numerous mitochondria. The nucleus of the dark cell is displaced toward the surface. Dark cells participate in fluid homeostasis to preserve the unique high-potassium and low-sodium content of the endolymph and also to maintain the calcium homeostasis in the inner ear. The vestibular supporting cells between the sensory cells are in general columnar. Small microvilli are found on the surface and a membrana reticularis is found at the upper surface of the supporting cells. Supporting cells may participate in the generation and the maintenance of the otoconia and the cupula. Supporting cells also participate in the structural support of the sensory cell as well as play an important role in mechanical transduction.