Fig. 4. AER formation is altered by loss of BMP function. (A,B) Noggin-infected stage 27 hindlimbs; in B, arrowheads point to remnant AER marked by Fgf8, broken lines outline the notched regions. (C-E) Stage 17 embryos showing the hindlimb region, arrows point to somite 28. (C) Uninfected and (D,E) Noggin-infected embryos. In D, Fgf8 expression is not detected in either limb; in E, there is a small region of Fgf8 expression in the left limb and, in the right limb, the anterior region of Fgf8 expression is absent and the posterior region is disrupted. (F,G) Two examples of Noggin-infected hindlimbs where arrows mark ectopic AERs on the ventral (v) side; in G, the limb is also notched. Anterior is towards the top, posterior is towards the bottom; all are dorsal views, except F, where ventral is towards the bottom, and G, which is a ventral view.
