Microprobe analyses of the potassium-calcium distribution relationship in predentine.
Apex regions of continuously growing incisors of Wistar rats were quickly dissected, shock-frozen in liquid nitrogen-cooled propane, freeze-dried at -80 degrees C and infiltrated with Spurr's resin. 400nm thick dry sections were cut with a diamond knife on an ultramicrotome. Relatively flat sections were transferred with an eye lash onto collodium coated aluminum grids. They were flattened with a glass stick and by placing another collodium coated aluminum grid just on top of the first one, exerting a uniform pressure. After carbon coating the sections were observed using the backscattered and secondary electron signals in a scanning microscope. The predentine was analyzed for calcium and potassium with an energy dispersive x-ray analysis system. The x-ray spectra revealed in the predentine regions with beginning dentine formation, near the apex, an uneven K-distribution with very low as well as more prominent x-ray peaks. The K peaks were always lower than those of calcium. In areas with advanced dentine formation, prominent K-peaks were always observed. They were normally higher than the Ca-peaks up to a distance of 5-10 microns from the dentine border. Closer to the dentine border the K concentration decreased while the Ca-peak increased. This might indicate that (besides Na) K is used to balance the negative charges of the macromolecules till K is replaced by Ca at the onset of apatite crystal formation.
Höhling
H J
HJ
Institute of Medical Physics, University of Münster, Germany.
Mishima
H
H
Kozawa
Y
Y
Daimon
T
T
Barckhaus
R H
RH
Richter
K D
KD
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D003804:Dentin / Q000378:metabolism* / Q000648:ultrastructure; D004577:Electron Probe Microanalysis; D009804:Odontoblasts / Q000378:metabolism / Q000648:ultrastructure; D011188:Potassium / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
D011188:Potassium; D002118:Calcium