BIOCOLLOIDS OF URINE IN HEALTH AND IN CALCULOUS DISEASE. III. THE MUCOPROTEIN MATRIX OF URINARY CALCULI 1

Abstract

The organic matrix was recovered from 676 urinary calculi by decalcification with chelating agents. All calculi had an organic matrix uniformly present from the center to the surface. Matrix material accounted for 2.5% (wt/wt) of 264 stones. Histochemical studies indicated both toluidine blue-0 metachromasia and PAS positive material in all calculi. Pooled cal-culous matrix contained 1/3 carbohydrate, largely galactose and hexo-samine in equimolar concentrations, and 2/3 protein in which 19 amino acids were found. The matrix of individual calculi had both an amorphous and a fibrillar structure. Partially decalcified stones exhibited alignment of crystalline material with fibrils. No urinary calculus was free of organic matrix, but 6 calculi were composed of matrix alone or of a small calcified center with a large cover of uncalcified matrix material. Although the inorganic ash content of these uncalcified matrices constituted 20-40% of the total weight of the specimen there was insufficient crystal formation to show opacification by ordinary roentgenography. The uncalcified matrices were intensely metachromatic with toluidine blue. Matrix deposition probably precedes calcification and may be essential step in urinary calculus formation.