Submicroscopic study of the vestibular dark cell area in human fetuses.

The purpose of this study was to determine the characteristic ultra-microstructure of the vestibular dark cell area related to inner ear metabolism at mid-term human embryonic development. This is when the general inner ear structures apparently attain their final development. Two types of epithelial cells, dark cells and light cells, are discernible in the vestibular dark cell areas. The morphology of the dark cells is described and their role in the metabolism of endolymph and otoconia is indicated. Little is known about the nature and presence of the light cells in mammals. The present study has revealed the ultra-microstructure of the light cells and indicates their secretory function in otoconia metabolism. The dark and light cells seem to be closely related to each other in the metabolic function of the dark cell area.