FINE STRUCTURE OF MURINE MAMMARY TUMOURS - RELATIONSHIP BETWEEN EPITHELIUM AND CONNECTIVE TISSUE IN NEOPLASMS INDUCED BY VARIOUS AGENTS

Fine structural changes have been observed at the junction between epithelium and connective tissue in murine mammary carcinomas of viral, chemical and unknown aetiology. The changes were similar in all these varieties of neoplasms and also appeared similar to those observed in comparable regions of carcinomas in other organs. They consisted principally of accumulation of fragmented basement membrane-like material, apparent reduplication of the basement membrane, extension of epithelial processes into the adjacent tissue and the destruction of the connective tissue in the vicinity of the epithelium. The significance of these findings is discussed and it is suggested that epithelial carcinogenesis may arise as a result of disturbance of interactions between epithelium and connective tissue. Marked myoepithelial cell proliferation was observed in methylcholanthreneinduced carcinomas and the significance of this observation is unknown. The author wishes to thank Professor R. L. Holmes and Dr. J. A. Sharp for advice and criticism during preparation of the manuscript. He is also greatly indebted to Dr. June Marchant for providing specimens of mammary tumours from her inbred strains of mice. © 1969, The British Empire Cancer Campaign for Research. All rights reserved.