Relationship of histology of Wilms' tumor to growth characteristics of nude mouse heterotransplants.

Eighteen Wilms' tumors (WIT), including classical triphasic WIT (blastema, tubules, and mesenchyme) and WIT variants (blastema and tubules, monomorphous tubules, multiloculated cysts, rhabdomyomatous WIT, and clear cell sarcoma), were heterotransplanted in nude mice. Ten (56%) tumors grew and were serially passaged. With two exceptions, the histology of the surgically resected tumors and heterotransplants was found to be similar. Tumors showing a prominent blastema component grew rapidly, whereas those with tubular epithelial or mesenchymal differentiation grew more slowly. Tumors injected s.c. consisted almost entirely of blastema, while tumors injected i.p. consisted of blastema with large areas of tubular epithelium. These results demonstrate that nude mouse heterotransplants of WIT closely resemble the surgically resected tumors from which they derive, that growth rates of WIT heterotransplants depend on the identity of the tumor cells, and that differentiation of WIT heterotransplants can be modulated, depending on the route of administration of tumor cells.