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Figure 4 | Frontiers in Zoology

Figure 4

From: New developmental evidence supports a homeotic frameshift of digit identity in the evolution of the bird wing

Figure 4

Inhibition of Shh signalling produces an experimental homeotic frameshift. (a) Triple injection with DiI (Red) and DiO (Green) along the antero-posterior axis at stage HH18, and subsequent fates at HH stage 31 (b, c, d). (e) Triple injection with DiI and DiO at stage HH18, and their fate at HH31 after cyclopamine application (f, g, h). Inhibition of Shh signaling results in bidactyl wings where a homeotic frameshift has occurred. Cells in positions that would normally give rise to middle (B) and posterior (C) digit morphologies now give rise to anterior (A) and middle (B) digit morphologies. Cells that would normally give rise to the anterior digit fail to develop into a digit. The posterior digit morphology is absent. (d) Merge of b and c. (h) Merge of f and g. (i) Comparison of injections made in control and cyclopamine-treated embryos. Scale bars: a, e—300 μm; b, c, d—1 mm; f, g, h—1 mm.

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