Differences in growth of transplants of liver, liver hyperplastic nodules, and hepatocellular carcinomas in the mammary fat pad.

Transplantation of fragments of normal rat liver autologously and isologously into the inguinal mammary fat pad permitted survival for up to 75% of grafts for 38 weeks, the longest interval studied. Similarly transplanted hepatocarcinomas grew rapidly and progressively in this site. Neither autologous or isologous transplants of liver hyperplastic nodules displayed obvious growth, although like normal liver, they also persisted for up to 38 weeks. Some persisting hyperplastic cells retained certain characteristic features, but others appeared to revert to a normal morphology. Thus, there is a stage in which hyperplastic cells do not possess the progressive growth ability of neoplastic cells and appear to be capable of reversion to a normal phenotype.