X-ray Microanalytical Determination of P, S and K Concentrations in the Gelatinous Membrane of the Utricle

Abstract

Electron probe X-ray microanalysis was used to determine the concentrations of P, S and K (C_P, C_s, C_K) in the gelatinous membrane of the mouse utricle. The otolithic membranes were plunge-frozen in liquid N₂, freeze-dried and carbon-coated. Quantitative analysis was carried out with an energy dispersive detector using the peak-to-background ratio method and different concentrations of KH₂PO₄ and K₂SO₄ salts dissolved in dextran solutions to calibrate the microprobe. P, S and K were measured and their concentrations plotted as bar graphs to study the frequency distributions. Regression analysis revealed a dependence between the concentrations of P and K (C_K = 1454.10 – 2.83 C_P, r = –0.68745, p < 0.05), and P and S (C_s = 43.18 + 0.23 C_P, r = 0.66949, p < 0.05); however, no correlation was found between C_K and C_P (r = –0.25424). The findings obtained in the present study show an inverse relationship between P and K ions, and direct relationship between P and S in the gelatinous membrane of the utricle.

Key Words:

• X-ray microanalysis
• scanning electron microscopy
• phosphorus
• sulfur
• potassium
• otolithic membrane
• biomineralization
• inner ear
• vestibule