Ultrastructural studies in Wilms's tumor

Abstract

Light and electron-microscopic features based on tissues from three human Wilms's tumors (nephroblastomas) are described and their significance discussed with respect to the histogenesis of the tumors. Tumor cells exhibited various levels of differentiation including well-formed tubules with fine structural characteristics of normal proximal tubules, and glomeruloid structures composed of epithelial cells with cytoplasmic processes suggesting the podocytes and foot processes of the glomerulus, but lacking blood cells, capillaries or mesangial cells. The glomeruloid structures contained what appeared to represent aberrant basement membrane formation corresponding to the PAS positive material observed with the light microscope. Electron microscopy revealed more definitive epithelial features than possible with the light microscope. These ultrastructural observations suggested an origin of Wilms's tumor in the metanephrogenic blastema.