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Figure 4 | Neural Development

Figure 4

From: Neural tube derived Wnt signals cooperate with FGF signaling in the formation and differentiation of the trigeminal placodes

Figure 4

Wnt signals are dependent on FGF signaling for the onset of Pax3 expression and subsequent neuronal differentiation in the cranial ectoderm. Cranial ectoderm explants isolated at the 3 somite stage (as depicted in the cartoon diagram) were grown in collagen gel cultures in the presence of Wnt3A (B, F), FGF8 (C), or Wnt3A and SU5402 (D, G). Explants were stained for the expression of Pax3 (A-D) and Brn3a (E-G). The presence of Wnt3A (B) but not FGF8b (C) was sufficient to induce the onset of Pax3 expression. However, Wnt3A is dependent on FGF signals to initiate Pax3 expression (D). When cranial ectoderm was isolated and cultured for 24 hours until approximately HH16, Wnt3A (F) resulted in expression of Brn3a. Similarly, the activity of Wnt3A was dependent on FGF signals to turn on Brn3a expression (G). Control explants cultured overnight were negative for the expression of Brn3a (E).

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