Lipid matrix of dystrophic calcification and urinary stone.

The concept that phospholipids, phosphatidyl serine (PS) in particular, play a role in tissue calcification has emerged recently and progressed rapidly. Membranous cellular degradation products upon various tissue injuries apparently serve as nidi of calcium apatite nucleation. In view of the strong affinity of calcium for PS, and the frequent occurrence of calcification in apposition to the inner surface of membrane where PS resides, it is concluded that exposure of PS to the extracellular fluid with a high calcium concentration upon cell injury is largely responsible for the dystrophic calcification. An abundance of membranous vesicles and other unidentified organic matrices were visualized in decalcified urinary stones. The findings also indicate the prospect of the role of degenerate cell membrane in stone formation as well. Furthermore, red cells adherent to bipyramid calcium oxalate dihydrate crystals apparently enhance crystal growth by mechanism analogous to the kink site formation. Lipid matrix in the form of membrane plays an important role in dystrophic calcification as well as calcium containing stone formation.