Neural Crest

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Neural Crest
The neural crest is a unique, transient,
migratory population of cells that show extreme
lineage diversity. Neural cresst is found in all
vertebrate embryos. The cells are induced at the
border between the neural plate and the
non-neural ectoderm.
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Neural crest migration
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Cranial crest migration
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Neural Crest Derivatives

• Neurogenic cells
• Pigment cells
• Mesenchymal cells

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Neural crest map
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Some of the cardiac defects produced by cardiac
neural crest ablation
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Trunk neural crest
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Early neural crest induction
Organizer
Ectoderm
Neural Crest Snail, Slug, FoxD3, Zic
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Double gradient model of NC induction Aybar and
Major, 2002

• Neural crest is dependent on a gradient of BMP
  in the ectoderm.
• Wnt inhibitors inhibit the anterior neural plate
  from generating neural crest.
• After neural tube closure, BMPs, Wnts, FGF and
  RA are required for late induction of NC.

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Why do different levels of the axis produce
different types of cells?

• Leblanc and colleagues
• In vitro, young Hensens node can regulate the
  expression of region-specific phenotypes in trunk
  neural crest cells
• A factor produced by Hensens node cell line
  stimulates the expression of two cranial-specific
  phenotypes (fibronectin and smooth muscle actin)
  in trunk neural crest cells and decreases their
  expression of a trunk specific phenotype
  (melanin)
• A metalloprotease that activates TGFbeta can
  mimic the action of Hensens node in trunk neural
  crest

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Are different derivatives generated directly from
progenitors with a full repertory of crest fates?

• Sieber-Blum M and colleagues
• In vitro clonal analyses of posterior
  rhombencephalic neural tube.
• Mesenchyme cells derived from the neural tube
  from somitic levels 1-3 contained 5 types of
  clone-forming cells smooth muscle cells,
  connective tissue cells, chondrocytes, sensory
  neuron precursors, serotonergic (putative
  enteric) neurons, and pigment cells.
• Another type of clone was totally
  pigmented,i.e. melanocytes only
• A third type consisted entirely of smooth
  muscle cells.

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Development of the face

• The upper face (forehead, eyes) is patterned
  mainly by the forebrain and optic vesicles. The
  olfactory placodes and all of the ectoderm and
  mesenchyme of the midface between the eyes and
  mouth are derived from the cephalic neural folds
  which form from the frontal prominence (Couly et
  al., 1985).
• The lower face (midface and jaw) is formed by the
  cephalic neural folds and pharyngeal arches 1 and
  2 (mostly 1).

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Cranial neural crest
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Figure 1
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Figure 2
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Table 1
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Figure 3
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Figure 4
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Figure 5
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Table 2
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Table 3