The microgenesis of some renal calculi.

We studied calcium oxalate stone formation in rats in which calculogenesis was induced by a diet deficient in pyridoxine (vitamin B6). We studied the sequence of stone formation using both a gross specimen transillumination technique, which is described, and histologic methods. A characteristic regional distribution of calculi is described and illustrated. Histologic studies reveal the interstitial site of calcium oxalate microlith formation. The progressive movement of these crystals through the tubular wall into the tubular lumen is described and illustrated. The formation of Randall's plaques is described and illustrated, as is a characteristic "geode" formation in the calyceal fornix. The significance of these findings is discussed and a new concept of stone formation proposed.