Ultrastructure of nodular renal blastema and sclerotic metanephric hamartoma

In the course of a prospective study of renal neoplasms involving rapid fixation by perfusion of the nephrectomy specimens, optimally perfusion-fixed tissue was obtained from complexes of nodular blastema and sclerotic hamartoma situated in a kidney with Wilms' tumour. Ultrastructure of these focal maturation defects showed great similarity to normal metanephric blastema and embryonal tubules as well as to blastemal and tubular components in diffuse nephroblastematosis and Wilms' tumours.