Figure 3. Feedback loops of secreted factors induce endoderm.

Figure 3Feedback loops of secreted factors induce endoderm.

Two positive feedback loops (in green and red) involving crosstalk between epiblast cells at the site of future primitive streak and trophectoderm allow to generate the high and long lasting levels of Nodal that induce endoderm. GDF1/3 act as Nodal co-factors in endoderm induction. A negative feedback loop (in blue) involving Lefty2 shuts down signalling activity to limit the amount of endoderm produced. Stars represent receptors. PEE ans ASE are characterized promoter elements. Questionmarks refer to putative interactions

From: Endoderm specification

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StemBook [Internet].
Cambridge (MA): Harvard Stem Cell Institute; 2008-.
Copyright: © 2008 Anne Grapin-Botton.

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