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. Author manuscript; available in PMC: 2014 Mar 18.
Published in final edited form as: Wiley Interdiscip Rev Dev Biol. 2011 Nov 17;1(1):3–15. doi: 10.1002/wdev.2

Figure 2. The VegT-nodal morphogen gradient in the early Xenopus embryo.

Figure 2

(A–C) vegT RNA (green) is anchored to the cortical cytoskeleton at the vegetal pole of the oocyte (A) but is released upon oocyte maturation and diffuses toward the animal pole during early cleavage stages (B). Local translation of vegT RNA generates a gradient of VegT protein (orange) that is restricted to nuclei of prospective endodermal cells located near the vegetal pole (B,C). VegT activates transcription of target genes such as nodal and other TGF-β family members, which encode secreted morphogens (C, small circles). Nodal is proposed to specify endodermal (endo) and mesodermal (meso) fate at high and moderate doses, respectively. Cells that are not exposed to nodal adopt an ectodermal (ecto) fate.