In Ctns proximal tubular cells (identified by apical megalin, in magenta; note decreased expression by the disease), lysosomes (defined by LAMP-1, red) show enlargement (small arrows) then distortion by crystals (arrowheads). Enlarged lysosomes accumulate the endocytic tracer (injected peroxidase, green), then progressively disconnect from active endocytic trafficking (i.e. become residual bodies) and can discharge their content into the tubular lumen (i.e. lysosomal defecation). Héloïse P. Gaide Chevronnay, De Duve Institute, Brussels Belgium