title: Microprobe analysis of human otoconia.
abstract: Utricular and saccular otoconia (N = 510) from 1 fetus (39th gestational week; Trisomy-18), 2 babies (1 1/2 and 2 months) and 3 adults (58, 61 and 77 years) were analysed with an energy dispersive X-ray microprobe. In all otoconia the elemental composition showed an extremely high concentration of Ca but also Na, Mg, P, S, Cl and K were identified. The presence of non-Ca elements was interpreted as being due to a protein nucleus of the otoconia. Non-Ca elements are more prominent during fetal age and early post-natally than later in life. Old age otoconia contained high concentrations of P which indicates that a ' phosphatization ' of aging otoconia occurs, i.e. calcite otoconia are transformed in situ into apatite by reaction with phosphate ions. The elemental composition of otoconia in Trisomy-18 was similar to that in early postnatal inner ears.
mesh_terms: D000368:Aged; D000375:Aging; D002118:Calcium / Q000032:analysis / Q000378:metabolism; D004577:Electron Probe Microanalysis; D005260:Female; D005333:Fetus / Q000032:analysis; D005612:Freeze Drying; D006706:Homeostasis; D006801:Humans; D007223:Infant; D008297:Male; D008855:Microscopy, Electron, Scanning; D008875:Middle Aged; D010037:Otolithic Membrane / Q000032:analysis / Q000196:embryology / Q000254:growth & development* / Q000378:metabolism / Q000473:pathology; D012444:Saccule and Utricle / Q000254:growth & development*
chemical_list: D002118:Calcium