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. Author manuscript; available in PMC: 2013 Sep 9.
Published in final edited form as: Dev Biol. 2008 Sep 5;323(2):152–165. doi: 10.1016/j.ydbio.2008.08.024

Figure 7. A gradient of Shh patterns the somite into mutually repressing muscle and cartilage cell fates.

Figure 7

Low levels of Shh promote the maintenance of Pax3 expression induced by Wnt signals. Medium levels of Shh, along with Wnt signals, promote the expression of the myotomal factors Myf5 and MyoD. High levels of Shh promote the expression of the sclerotomal factors Nkx3.2, Sox9 and Pax1, and simultaneously repress expression of both dermomyotomal and myotomal markers. Mutual repression by Pax3 and Nkx3.2 ensures that cells adopt either a dermomyotomal or sclerotomal cell fate. While Pax3 induces the expression of MyoD/Myf5 and promotes somitic myogenesis, Nkx3.2 and Sox9 promote somitic chondrogenesis.