Possible mechanisms of floor plate development in the chick embryo. Panels A and B show transverse sections through neural tube-stage chick embryos. Shh gene expression is detected by in situ hybridization histochemistry. (A) Restriction of Shh expression to the notochord at early stages of caudal neural tube development. (B) Expression of Shh by both the notochord and floor plate at late stages of neural tube development. (C) The position of notochord (N) and floor plate (FP) cells. (D) A model of floor plate development in which floor plate and notochord cells derive from a common progenitor cell in the node, independent of inductive signaling. (E) A model in which the Hedgehog-mediated induction (red arrows) of floor plate cells begin in the node and continues after neural tube closure. (F) A model in which the induction of floor plate differentiation occurs primarily after neural tube closure. Floor plate cells may also serve as a source of Hedgehog signals that induce additional neural tube cells to acquire a floor plate fate.

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Science, Vol 282, Issue 5394, 1654-1657 , 27 November 1998 [HELP with high resolution image viewing] [Return to Article]
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