ABSTRACT
This chapter discusses some of the issues that have an impact on the mouse liver tumor controversy. Heterogeneity of marker appearance is observed in the staining patterns of many tumors. In our experience, the most consistent markers in mouse liver carcinogenesis are the altered hematoxylin and eosin staining of foci on routine paraffin sections. Tumor data from cancer bioassays are clearly a useful tool for hazard identification and assessing potential carcinogenic activity of environmental chemicals. Many of the current problems associated with diagnosis and significance of mouse liver tumors stem from the lack of understanding of the various stages in the carcinogenic process. Similar controversies concerning the pathogenesis of mouse tumors exist for liver lesions in rats and other species. Many of the same molecular alterations found in human tumors are detected in mouse liver tumors. Most investigations that analyze H-ras mutations in mouse spontaneous liver tumors have been conducted using the B6C3F1 mouse.
