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. Author manuscript; available in PMC: 2016 Dec 2.
Published in final edited form as: Dev Biol. 2012 Jan 3;363(1):247–257. doi: 10.1016/j.ydbio.2011.12.037

Fig. 4.

Fig. 4

AER and ventral ectoderm Smad1/Smad5 signaling is required to repress expression of Fgf8 in the interdigital distal ectoderm. (A, B) Whole mount in situ hybridization of E10.5 mutant forelimb buds showed no expansion of Fgf8 expression along dorsal–ventral or anterior–posterior axis. (C–F) Section in situ hybridization of E11.5 mutant forelimb buds showed that the expression of AER marker Fgf8 (C, D) and En1 (E, F) was restricted in AER and ventral ectoderm along the dorsal–ventral axis that was comparable with the control. The morphology of AER in the Smad1/5 mutant did not show any abnormality. (G–J) Ectopic Fgf8 expression was observed in the forelimb interdigital ectoderm of the Smad1/5 mutants at E13 (white arrowhead) and the Fgf8 expression was punctuate throughout the distal ectoderm of the mutants. (K, L) Fgf8 expression faded in AER over interdigit of Smad1/5 mutants at E13.5 indicated by white arrows. Arrows indicate the major axes: A, anterior; P, posterior; D, dorsal; V, ventral; Di, distal; Pr, proximal. Scale bars: A–B=500 µm; C–F=50 µm; G–L=1 mm.