Histological evaluation showed large interstitial mineral deposits that displaced the surrounding renal tubules. In addition, we observed small intraluminal mineral deposits in cortical and medullary tubular segments of the kidneys of Npt2a-/- and double-mutant mice (Fig 4A). Transmission electron images showed concentric spheres of similar morphology in Npt2a-/- and double-knockout mice (Fig 4B) as previously described for Npt2a-/- mice by us [13, 43] and others [33, 34]. No mineralization was observed in renal vasculature or in the renal pelvis of our mice.