ELECTRON MICROSCOPICAL AND MICROPROBE OBSERVATIONS ON CELL SHEATH OF STIMULATED OSTEOCYTES

Rats were treated with 0.6 mg (0.1 mg twice a week) of dihydrotachysterol and the following electron microscopic and electron-probe X-ray microanalytical findings were made: 1. The periosteocytic mucopolysaccharide sheath is definitely enlarged in the treated animals. In it were found, in variable quantities and distribution, collections of round or needle-shaped electron-dense particles. 2. By electron-probe X-ray microanalysis, high concentrations of calcium and phosphorus were detected in the cell sheath, where the Ca/P ratio may reach the value of pure apatite. The electron-dense particles are considered to be calcium phosphate nuclei. It is postulated that in consequence of the pathologically increased calcium turnover, calcium salts are set free from the mineralized matrix surrounding the osteocyte lacuna in such quantities as to become morphologically detectable in the cell sheath. © 1969 Springer-Verlag.