ROLE OF ORGANIC MATRIX IN URINARY STONE FORMATION - AN ULTRASTRUCTURAL-STUDY OF CRYSTAL MATRIX INTERFACE OF CALCIUM-OXALATE MONOHYDRATE STONES

Human calcium oxalate monohydrate (COM) urinary stones were decalcifie d by treatment with a mixture of ethylenediaminetetraacetic acid (EDTA ) solution and Karnovsky's fixative after embedding in bactoagar. Deca lcified stones were examined by light microscopy, and also by scanning and transmission electron microscopy. Stones had distinct nuclei that were occupied by amorphous or apatitic calcium phosphate or aggregate s of spherulitic COM crystals. EDTA insoluble matrix was ubiquitous in stones and consisted largely of finely matted fibrous material. It wa s organized in concentric laminations in the peripheral area of the st one but appeared highly disorganized in the stone center. Crystals wer e replaced by crystal ghosts. Organic matrix was present both inside t he crystals and in the intercrystalline spaces. The study indicates a very close association between crystals and organic matrix. The relati onship appears to begin early in crystal formation and persists throug hout the formative and growth phases of the urinary stones.