Morphology of crystals in calcium oxalate monohydrate kidney stones

Both scanning electron microscopy and atomic force microscopy (AFM) have shown that calcium oxalate monohydrate kidney stones are made up from arrangements of sub micron crystals. The purpose of this investigation was to determine the morphology of these crystals which was obscured by the presence of organic matrix in our earlier study. Sections of stones were treated to remove the protein component of the matrix and then imaged using AFM. Images obtained after proteolysis show that the crystals are in the form of plates stacked on (100) surfaces. These results were confirmed by scanning electron microscopy observations from selected regions of calcium oxalate kidney stone surfaces. The observed crystal sizes are consistent with both the known matrix mass fraction and crystallite growth in the passage through the collecting duct.