In vivo maturation of SEES teratoma. A. Teratoma at 17 weeks after implantation of SEES-3 cells. B, C. Teratomas at 31 weeks after implantation of SEES-3 cells. D, E, F. Teratomas at 32 weeks after implantation of SEEDS-3 cells. G. High power view of intestinal epithelium (inlet in panel D). Dashed line: the intestinal lumen became enlarged due to accumulation of the mucus. H. High power view of intestinal epithelium (inlet in panel G). Note that intestinal epithelium were fully differentiated. I. High power view of epidermis with prominent keratinization (inlet in panel E). Dashed line: the epidermal cyst became enlarged due to accumulation of the keratinizing material. J. High power view of epidermis with distinct 4 layers, i.e. basal, spinous, granular, and horny layers (the inlet in panel I).