Hearing research
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The aim of this study is to determine the stages of appearance, morphology, crystallographic structure and chemical composition of otoconia during the inner ear development of an urodele amphibian, Pleurodeles waltl. The first otoconia are detected in the otocyst. Near hatching, calcitic otoconia are polyhedral in the saccule and cylindrical in the utricle. ⋯ Energy dispersive X-ray spectroscopy (EDXS) elemental analysis of the otoconia reveals a high quantity of calcium with trace quantities of sodium, magnesium, phosphorus, sulfur, chlorine and potassium. However, magnesium and sulfur have a lower concentration in lagenar aragonitic otoconia than in utricular and saccular calcitic ones. As in adults, trace amounts of strontium are only found in aragonitic otoconia.