Mouse CHEB kidney. (A) Light microscopy, toluidine blue staining (original magnification × 500): strong staining of crystalline inclusions in the cytoplasm of proximal tubular cells. (B) Immunofluorescence microscopy, anti-κ human conjugate (original magnification × 500): these inclusions are strongly stained with a pattern similar to that found in patients’ CHEB tubular proximal cells. Electron microscopy: (C) original magnification × 1,200; (D) original magnification × 25,000: these crystalline inclusions are osmiophilic and similar to that found in patient CHEB with the same 60 Å periodic striation.