[Histogenesis of experimental renal tumors in mice]

Epithelial kidney tumours induced in CBA male mice by 1,2-dimethylhydrazine were studied histochemically and immunohistochemically. Histologically, 48 tumours studied were diagnosed as clear-cell, acidophilic or mixed adenomas located in the renal cortex. Gamma-glutamyl transpeptidase (GGT) was strongly positive in normal proximal convoluted tubules, slightly positive in the cells of Bowman capsule and negative in 47 of 48 tumours examined. Antibodies against the new antigen obtained from the mouse liver oval cells and called A6 antigen were also used. This antigen in normal kidney is negative in proximal tubules but always positive in distal tubules and collective ducts. It was also positive in all 47 GGT-negative tumours. One tumour was GGT-positive and A6 antigen-negative. The conclusion is made that the majority of renal cell adenomas in mice most likely originate from the collective duct system and not from the proximal tubules.