The Kinetics of the Organ-specific Metastasis of a Transplantable Reticuloendothelial Tumor¹ Free

Reticuloendothelial tumors tend to metastasize to specific organs and are, therefore, ideal tools for testing the “seed-soil hypothesis” of metastasis.

A transplantable reticulum-cell sarcoma which selectively metastasizes to the spleen was used. Equal numbers of cells were injected into both kidney and spleen of six C3H mice. At the time of sacrifice, growth in the spleen was always considerably greater than in the kidney. In no case was the mitotic index greater in the spleen than the kidney. Since the growth rate equals the mitotic rate minus the cell loss rate, one may conclude that the reason for the relative lack of growth in the kidney is that the rate of tumor cell loss is greater there than in the spleen. Additional studies demonstrate that these tumor cells will migrate to the spleen if implanted in other locations, including the kidney. This tendency to migrate out of organs other than the spleen may account for the apparent selective metastatic behavior of this tumor.