Intracellular and intraluminal aspects of renal calculosis in the marine mollusc Macrocallista nimbosa.

The intracellular and intraluminal development of renal calculi in the bivalved mollusc Macrocallista nimbosa was investigated by histologic techniques. The origin of calculi is within the renal tubule cell. Early events involve the formation of a stone precursor into which are incorporated calcium salts, heavy metals, and mucopolysaccharides. The stone is eventually extruded into the tubule lumen where it continues to grow by epitaxy and aggregation. Various forms of calcium phosphate calculi were identified, including hydroxylapatite, whitlockite, brushite, and chlorapatite.