Electron probe X-ray microanalysis of otoconia in guinea pig inner ear: a comparison between young and old animals

Using the electron probe X-ray microanalysis technique, the elemental composition of otoconia was analysed in both young and old normal pigmented guinea pigs. Calcium concentration in both the utricular and the saccular otoconia was lower in the old animals, which indicates that the loss of calcium from otoconia and/or decrease in calcium ion uptake may occur in the old animals. The present study has established that calcium and other elements (P, S, Cl and K) in the otoconia of the young animals are related via a linear function, indicating that P, S, Cl and K are present in the mineral phase of the otoconia. The associations of Ca-P, Ca-K and Ca-S are not maintained in the old animals. It has been suggested that the aging phenomenon may influence the ionic metabolism in the vestibular end organs resulting in the altered mineral composition of otoconia.