Human hypoblast formation is not dependent on FGF signalling.
Bottom Line: These differentiation processes are associated with restricted expression of key transcription factors (Cdx2, Oct4, Nanog and Gata6).However, the formation of hypoblast in the human is apparently not dependent upon FGF signalling, in contrast to rodent embryos.Nonetheless, the persistence of Nanog-positive cells in embryos following treatment with FGF inhibitors is suggestive of a transient naïve pluripotent population in the human blastocyst, which may be similar to rodent epiblast and ES cells but is not sustained during conventional human ES cell derivation protocols.
Affiliation: Wellcome Trust Centre for Stem Cell Research, University of Cambridge, Cambridge CB2 1QR, UK.Show MeSH
Mentions: We first examined human embryos at 6 days post-fertilisation. Nanog is confined to a few inner cells within the embryo (Fig. 1A). Gata6 and Oct4 are widely expressed throughout the embryo, with levels varying between individual cells, consistent with previous data (Cauffman et al., 2005; Cauffman et al., 2006; Chen et al., 2009; Kimber et al., 2008). Some inner cells exhibit high levels of Nanog and low levels of Gata6 (Fig. 1B, arrows), whilst in other cells both markers are expressed at about the same level (Fig. 1B, arrowheads). This pattern is similar to that observed in the early mouse blastocyst (Plusa et al., 2008).
Affiliation: Wellcome Trust Centre for Stem Cell Research, University of Cambridge, Cambridge CB2 1QR, UK.