Suppression of Tumors and Transplants of Fetal Digestive Tract Growing in Newborn Mice

Abstract

Transplants of different sections of fetal digestive tract (DT) grew progressively and formed huge organ-like cysts in all adult BALB/c syngeneic recipients. The histologic structure of these cysts was similar to that of corresponding sections of the gastrointestinal tract. Some of these cysts underwent spontaneous malignant conversion 13–16 months later: Adenocarcinomas of the small and large intestines, solid epithelial tumors, and sarcomas or leiomyosarcomas developed. Transplantable strains were obtained from these tumors. The growth of organ-like cysts, formed from fetal DT, was markedly retarded in the newborn recipients as compared with that in adults. Stomach and large-intestine cysts appeared in 100% of the newborn mice, but they grew much more slowly than the cysts in the adult recipients. Cysts from fetal small-intestine transplants appeared later and developed only in 43–47% of the newborn recipients, as compared with 100% of the adults. Growth of transplantable tumors of DT was significantly retarded in newborn recipients as compared with that in adults. The greatest difference in tumor growth in newborns and adults occurred in transplantation of the small-intestine adenocarcinoma. It is assumed that newborn mice have certain nonimmunologic properties that specifically influence the growth of transplants and tumors of DT, particularly tumors of the small intestine.