BeschrijvingFormation of the primitive body plan following gastrulation in the mouse.png
Figure 2. Formation of the primitive body plan following gastrulation in the mouse. (A) Right hand panel: Pro-Nodal secreted from the extraembryonic ectoderm (EXE) is converted to Nodal in the presence of the convertases Furin (F) and Pace4 (P). Nodal acts on the visceral endoderm (light green cells) to regulate the expression of pro-Nodal and production of Nodal. A feedback system is established between Nodal, BMP and Wnt3 causing primitive ectoderm (PrEct) cells on the posterior side to ingress through the primitive streak, which continues to elongate in a proximal-distal direction from 6.5 dpc. Cells that migrate through the primitive streak form the definitive mesoderm (ME) and endoderm (DEnd) germ layers. Left hand panel: On the anterior side of the embryo, the anterior visceral endoderm (AVE; dark green cells) secretes the Nodal antagonists Cer1 and Lef1, and the Wnt3 antagonist Dkk1, inhibiting Nodal and Wnt3 signaling and thus establishing the definitive ectoderm germ layer by 7.0 dpc. BMP4 is secreted from the EXE, while BMP4 antagonists including Noggin (Ngn), Chordin (Chd) and Follistatin (Fsn) are secreted from the Node (N), establishing a gradient of BMP4 across the definitive ectoderm, such that by (B) 7.5 dpc, BMP4-mediated SMAD signaling in the proximal definitive ectoderm produces surface ectoderm (SE) while the distal definitive ectoderm differentiates to neurectoderm (NE) in the absence of SMAD signaling. (C) Following the completion of gastrulation at ~7.5 dpc, the ME differentiates to give rise to the paraxial mesoderm (pME) and lateral plate mesoderm (lpME), the DEnd produces the gut tube (GT) and the NE gives rise to the neural tube (NT). Additional key: EXM/En, extraembryonic mesoderm/endoderm; Prox, proximal; Dist, distal; A, anterior; P, posterior.
Rachel A. Shparberg, Hannah J. Glover, Michael B. Morris
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{{Information |description=Figure 2. Formation of the primitive body plan following gastrulation in the mouse. (A) Right hand panel: Pro-Nodal secreted from the extraembryonic ectoderm (EXE) is converted to Nodal in the presence of the convertases Furin (F) and Pace4 (P). Nodal acts on the visceral endoderm (light green cells) to regulate the expression of pro-Nodal and production of Nodal. A feedback system is established between Nodal, BMP and Wnt3 causing primitive ectoderm (PrEct) cells o...