Metaplasia and metastasis of a rat tumor

Abstract

We reported to this society on several previous occasions some facts regarding a tumor of the rat which we have propagated for more than two years. This tumor is now in its twelfth generation. The original tumor was of complex histological structure and has been regarded by us as consisting predominantly of a tissue of sarcomatous nature and to a less extent of irregular tubular formations resembling structures seen in certain endotheliomata. In the fifth generation of one series of transplantations, metastases were first noted in the regional lymphatic glands. In all previous generations the metastases were to the lungs and the kidneys; and in the other series this change in properties has not been observed. In the succeeding generations between the fifth and the eleventh, of the particular series mentioned, the lymphatic metastases have grown more common and more widely disseminated. Coincident with this change in properties of the tumor, a modification in the histological structure has been noted; the tumor has become progressively more and more adenomatous in appearance until now it has entirely cleared itself of that part which had been taken to resemble sarcoma. Hence nietaplasia of the tumor in the direction of carcinoma has taken place, with which change is associated the acquisition of the property of involving the nearby and distant lymphatic glands in its growth.