Epithelial and Stromal Roles in Carcinogenesis. II. Tumor Development in Internal Transplants of Skin and Epithelium Treated With 3-Methylcholanthrene2

Abstract

The site of action of chemical carcinogens was studied by painting the skin with 3-methylcholanthrene, followed by separate transplantation of the epithelium and stroma from the painted areas. Full-thickness skin was similarly transplanted after carcinogen application. All transplants were placed internally, which thus avoided the uncertainty of the origin of the epithelium occasioned by the ingrowth of neighboring epithelium which occurs when skin is transplanted to external sites. Normal skin and fully developed tumors survived and proliferated after transplantation. Tumors did not develop in the transplants of pure epithelium. Few tumors developed in transplants of full-thickness skin, unless tumors were already present in the skin before it was transplanted. Tumors did develop in the painted sites from which transplants were taken. Experiments have eliminated the strain of mice used, the transplantation site, and transplant necrosis as primary factors in the failure of transplants to develop tumors. Failure was not due to inhibiting factors in the host caused by exposure to carcinogen or by the growth of tumors in the areas painted, since no tumors developed in transplants made to normal mice of the same strain. It was concluded that one of the ultimate steps in carcinogenesis was inhibited by transplantation.