Loss of posterior hox expression in embryos lacking Cdx1a/4. Expression of hoxb5a (A,B), hoxb6a (C,D), hoxb7a (E,F) or hoxa9a (G,H) in wild-type controls (wt) (A,C,E,G) and in embryos that received an injection of 1 ng cdx1aMO and 1 ng cdx4MO (B,D,F,H) at 22 hpf. hoxb5a, hoxb6a, hoxb7a and hoxa9a are expressed in the spinal cord. hoxb5a is expressed at the level of somite 1 and posterior to it. hoxb6a is expressed at the level of somite 2 and posterior to it. hoxb7a and hoxa9a are expressed at the level of somite 4 and posterior to it. In the cdx1a/4 morphant embryos, hoxb5a or hoxa6a-negative domains were detected in the posterior neural tissue (arrowhead in B and D). Scale bar: 100 μm.
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