Body and kidney parameters and renal morphology.

<p>Allopurinol 75 μg/ml causes a reduction of body weight (a) and an increase of kidney/body weight ratio (b) only in KO mice. Representative macroscopic images of dissected fresh renal tissue after treatment with allopurinol 75 μg/ml or vehicle (c). Allopurinol does not cause macroscopic changes in HPRT^+/- and WT mice. The vehicle-treated HPRT^-/- kidneys have a normal appearance as well. Instead, allopurinol administered to HPRT^-/- animals produces profound modifications of the renal structure, with pale and yellowish appearance. This is shown in more details in panel (d), where yellow deposits can be observed in the cortex (black arrows) and yellow streaks in the medulla (white arrows). Analysis of the fresh tissue by polarized light microscopy demonstrates that the deposits are of crystalloid nature (e). *p<0.05 as compared to vehicle-treated HPRT^-/-. Scale bars: 1 mm.