ORGANIC MATRIX OF HUMAN URINARY CONCRETIONS

Concentric laminations, radial striations, frond formation and spherules are morphologic characteristics of native human concretions occurring in any segment of the urinary conduits from nephron to external meatus. The organic matrix is invariably so structurally related to these gross physical characteristics as to justify the assumption that it has a definitive architectonic role in the morphology of all concretions. Intermolecular bonding between matrix molecules appears to be established by gross, histological and electron microscopic examination. Matrix composition is remarkably constant for calculi of any type of crystalline content. The molecular composition is predominantly of molecules of low molecular weight, high solubility in their native states, and relatively low concentration in the urine of patients who form calculi. Selectivity is clearly a factor in matrix formation from urinary macromolecules. Matrix deposition unquestionably precedes crystal formation in all forms of experimental intranephronic calculosis. The occurrence of matrix calculi" and recrystallization of decrystallized cystine stone matrices suggest that matrix precedes crystal deposition in at least some human concretions. Calcium and phosphate are universally present in calculus matrix even after all microscopic or petrographically demonstrable crystals have been removed. Mineralization in terms of inorganic ion accretion by matrix is a distinct possibility. This may play a role in concrement formation by decreasing the solubility of matrix molecules. The molecular epitactic nucleation of hydroxyapatite may well be a characteristic of the majority if not of all calculus matrices. © 1968."