Relative susceptibility of various organs to tumor transplantation.

Metastasis of neoplasms is a complex process involving several steps. First, is the separation of cells from the main tumor; then follow invasion of a vessel, transport, arrest, penetration of the ves sel wall, and, finally, establishment and growth in the new site with new stroma and vascular supply. Some aspects of this process have been discussed in recent papers from this laboratory: (a) the condi tions governing the release of tumor emboli from the primary tumor (13) and (6) the distribution of tumors in various organs after tumor emboli have been artificially introduced into the blood stream (2). The present investigation is concerned with a third aspect of metastasis, the comparative ability of various organs to support tumor growth—that is, to supply tumor cells with stroma, adequate blood supply, and a generally suitable environ ment. This problem may appropriately be studied by implanting fragments of tumor in various or gans and observing incidence of "takes" and rate