Hepatocyte diversity has long been known, yet it remains difficult to analyze the distinct properties of the various hepatocyte populations under physiological conditions. A unique subpopulation of periportal hepatocytes were recently identified by UC San Diego researchers. These cells are located in the limiting plate and express Sox9 and HNF4alpha, a hepatocyte transcription factor. The cells were termed HypHP (hybrid hepatocytes) and are a hybrid between a hepatocyte and a duct cell. Transcriptomic and immunohistochemical analyses show expression of hepatocyte-specific genes as well as a small number of genes that are preferentially expressed in bile duct cells. In the unchallenged liver, HypHP are quiescent for at least 9 months after birth, but during chronic liver damage they proliferate and serve as a source of new hepatocytes that repopulate the liver. Chronic liver disease remains the leading cause of liver transplantation, an expensive procedure which is a cause of morbidity and mortality. Others have suggested cell transplantation, such as stem cells, as an alternative. However, suitable matches are difficult to find. Hepatocytes can be derived from induced Pluripotent Stem Cells (iPSCs), however, this procedure does not generate fully functioning hepatocytes. Other approaches for cell transplantation use ductal cells, which also does not generate fully functional cells.