Magnesium as an intrinsic component of human otoconia

Abstract

Objectives: To investigate morphology changes of artificial otoconia (CGC) in the presence of magnesium during growth under in vitro conditions.

Methods: Investigating human otoconia by environmental scanning electron microscope and determining their magnesium content by energy-dispersive X-ray microanalysis (EDX). Comparing structural and morphological data of human and artificial otoconia (CGC, Ca₁Mg₀) without and with magnesium substitution (Ca_1-xMg_x).

Results: EDX- and X-ray data reveals that the inorganic component in human otoconia consists of calcite containing a minor amount of magnesium substitution (Ca_1-xMg_x). CGC containing magnesium (length 397.0 ± 146.4 µm, diameter 325.6 ± 100.1 µm) are slimmer and significantly smaller (p < .01) than pure CGC (length 548.6 ± 160 µm, diameter 373.0 ± 110.4 µm) and reveal a significant influence on the final morphology. The length/diameter ratio is significantly higher by incorporation of magnesium into CGC (1.84 ± 0.25 µm versus 1.48 ± 0.11 µm in pure CGC, p < .01), which brings the overall shape to a close relationship with human otoconia (1.98 ± 0.08 µm).

Conclusions: Magnesium is an intrinsic component of human otoconia by partial substitution of calcium in the calcite crystal structure (Ca_1-xMg_x) and affects the development of the shape of artificial otoconia (calcite gelatin composites, CGC).

Chinese abstract

结论：镁部分置换方解石晶体结构（Ca1-xMgx）中的钙。它是人耳耳蜗的内在成分, 并影响人造耳石（方解石明胶复合物, CGC）形状的发展,

目的：研究在体外条件下生长过程中, 镁的存在对人造耳蜗（CGC）的形态变化的影响。

方法：用环境扫描电镜观察人耳耳蜗, 并用能量色散X射线微量分析仪（EDX）测定其镁含量。比较没有镁置换和用镁置换（Ca1-xMgx）的自然耳蜗和人造耳蜗（CGC, Ca1Mg0）的结构和形态学数据。

结果：EDX和X射线数据显示, 人耳蜗中的无机组分由含有少量镁取代物（Ca1-xMgx）的方解石组成。含有镁的CGC（长度397.0 ± 146.4μm, 直径325.6 ± 100.1μm）比纯CGC（长度548.6 ± 160μm, 直径373.0 ± 110.4μm）更细并且显著更小（p <0.01）, 显示出对最终形态所起的重大作用。通过向CGC中加入镁（1.84 ± 0.25μm, 相对于纯CGC中的1.48 ± 0.11μm, p <0.01）, 长度/直径比率显著提高, 使得其整体形状与人耳（1.98 ± 0.08微米）接近。

Keywords:

• Otolith organs
• otoconia
• calcium
• magnesium
• calcite substitution
• calcium carbonate
• saccule
• utricle

Disclosure statement

No potential conflict of interest was reported by the authors.