Endolymph chemistry and otolith growth in fish

Otoliths are composed of 99% CaCO3 in the aragonite form which is deposited daily onto an organic matrix. The mineralisation process takes place in an acellular medium, the endolymph, which is secreted by the inner-ear epithelium. The present review is mostly devoted to ionic and organic endolymph components (concentration and spatial distribution) in relation to otolith growth, with a special interest to the ionic supply from plasma to endolymph and to the biochemical relationships between endolymph and otolith matrix.