Studies of tumor cell origins in mosaics

The available data on chemical carcinogenesis with methylcholanthrene in mosaic mice and studies of atherosclerotic plaques in human and experimental animal G6PD mosaics have been reviewed. The MC studies in two different kinds of mosaic mice demonstrate the importance of understanding normal tissue architecture before making inferences regarding the cellular kinetics of tumor origin. The analysis of the MC studies also indicates a large cellular target size for this carcinogen. The current data on atheromas in mosaic humans and animals do not support the classical idea of an injury-repair mechanism of plaque origin, and leave the possibility open that the monoclonal tendency of atheromas could indicate a tumorigenic type of mechanism in their development.