Electron micrographs of kidney biopsy specimens showing glomerular and tubular basement membrane of Pt1. (A) Thickening and splitting of the tubular basement membrane (arrow) and granular inclusion of electron-dense particles (dotted arrow). Magnification × 17 000. (B) Focal thickening and irregularity of the glomerular basement membrane with splitting of the lamina densa (arrow) and inclusion of electron-dense particles (dotted arrow). Magnification × 17 000.