In Vitro Induction of Potential Primordial Germ Cells from Mouse Embryonic Stem Cells by Culture with Undifferentiated Gonadal Cells Tomioka, Ikuo and Honma, Yuji and Sasada, Hiroshi and Sato, Eimei, Journal of Mammalian Ova Research, 25, 37-43 (2008), DOI:http://dx.doi.org/10.1274/jmor.25.37