Figure 2.

Origins of mammalian pluripotent cells. In the green column on the left are the developmental stages and in vivo origins from which mammalian pluripotent stem cells have been derived. In the pink column in the middle are the stem cell types that can be propagated in vitro. In the blue column on the right is indicated which in vitro cultured mouse cells can participate in all three germ layers including germ cells as determined by the chimera assay. In the same column is indicated which in vitro cultured mouse cell types can restore spermatogenesis as determined by the testis transplantation assay. Blue arrows indicate the derivation of in vitro cell lines from in vivo origins, yellow arrows indicate in vitro transformation/differentiation of one cell type into another, green arrows indicate in vivo functionality tests of in vitro cultured cells. White numbered squares refer to studies performed in mice and red numbered squares refer to studies performed in human: ¹Evans and Kaufman (1981), Martin (1981); ²Thomson et al. (1998); ³Chou et al. (2008); ⁴Brons et al. (2007), Tesar et al. (2007); ⁵Matsui et al. (1992), Resnick et al. (1992); ⁶Liu et al. (2004), Shamblott et al. (1998), Turnpenny et al. (2003); ⁷Okita et al. (2007), Takahashi and Yamanaka (2006); ⁸Takahashi et al. (2007); ⁹Kanatsu-Shinohara et al. (2004), Ko et al. (2009), Seandel et al. (2007); ¹⁰Conrad et al. (2008), Golestaneh et al. (2009), Kossack et al. (2009), Mizrak et al. (2009); ¹¹Guan et al. (2006); ¹²Kanatsu-Shinohara et al. (2003); ¹³Bao et al. (2009), Guo et al. (2009), Silva et al. (2009); ¹⁴Guo et al. (2009); ¹⁵Nayernia et al. (2006).