Genes that are specific to germline and embryonic development can be activated in many tumors. Here, we show that germline traits that are present in human hepatoblastoma cells might be associated with the malignant behaviors of these tumor cells. In culture, single human hepatoblastoma cells differentiated into germ cell-like cells, which further developed into oocyte-like cells and formed parthenogenetic blastocyst-like structures. The germ cell-like cells and their embryonic derivatives from hepatoblastoma cells may favorably give rise to xenograft tumors with embryonal/germline traits and intrahepatic metastasis. These findings suggest that germline potential can be spontaneously activated in human hepatoblastoma cells and it might be important for tumor formation and metastasis. (c) 2013 Elsevier Inc. All rights reserved.