Observation of the morphology and calcium content of vestibular otoconia in rats after simulated weightlessness

ConclusionsReduction in bone formation may have been the main reason for the lower calcium content of the otoconia after simulated weightlessness in rats. The head-ward distribution of blood volume may explain the morphological changes observed in the middle and inner ears.ObjectiveTo observe morphological changes in the vestibular organs and measure the calcium content of otoconia in rats after simulated weightlessness.Material and methodsWe used a tail suspension model of simulated weightlessness and then investigated changes in the vestibular organs using scanning electron microscopy and X-ray microanalysis.ResultsIn comparison to untreated rats, the vestibular otoconia of the rats subjected to simulated weightlessness were small, irregularly shaped or fissured, and were arranged loosely and out of order. In addition, the calcium content of the otoconia was markedly decreased.