The Eker renal tumor rat. Tumor transplantability and a re-evaluation of tumor histology.

Further histological findings for the naturally occurring kidney tumor of the Eker rat included the unusual location of the tumor entirely within the medulla rather than in the more usual site within the kidney cortex; the presence of psammoma bodies, and metastases of the tumor in one animal. The kidney tumors were shown to be transplantable with a latent period of about nine months. Histologically, the transplanted tumor, even at the twenty-eight transplant generation, maintained the cellular characteristics of the primary. The histological and transplant data allow the classification of the definitive tumor as a primary adenocarcinoma. The suitability of the tumor as an animal model for human renal carcinoma is suggested.