These images demonstrate extensive calcification of the stromal tissue of the medulla/renal papilla.
Low power histological image of medullary rays (empty tubules radiating from the left of picture) extending into a renal papilla that projects into a minor calyx. The extent of the 'dark purple' areas of calcification in the medulla/papilla is well demonstrated at this level of magnification.
High power histological image of the tip of the renal papilla (upper) including the intertubular calcification (dark purple). The intact residual medullary rays are partly atrophic. The image also demonstrates the lining urothelium of the minor renal calyx