Skip to main content
. 2017 Feb 28;5:14. doi: 10.3389/fcell.2017.00014

Figure 1.

Figure 1

Shh as a morphogen in the chick wing bud. (a) Sonic hedgehog (Shh) expression in the polarizing region at the posterior margin of the early chick wing bud (Riddle et al., 1993). (b) A gradient of Shh in the chick wing bud (blue shaded numbers) specifies antero-posterior positional values for three digits (1, 2, and 3) in cells adjacent to polarizing region over 12 h. (c) Chick wing digit skeleton with polarizing region descendants fate-mapped by GFP-expression (green) (Towers et al., 2011). Digits form in tissue adjacent to descendants of the polarizing region that form narrow strip of cells along posterior wing margin. (d) Chick wing bud with anterior polarizing region graft expresses Shh at both anterior and posterior margins (Towers et al., 2011). (e) Mirror-image symmetrical positional values specified as in (b) as a result of Shh being produced by both graft and host. (f) Chick wing digit skeleton pattern with grafted polarizing region (d) and progeny fate mapped by GFP expression (Towers et al., 2011). Six digits form in an anterior to posterior pattern 3-2-1-1-2-3 and grafted polarizing region descendants form narrow strip of cells along anterior wing margin. In all cases, data shown is representative of data in the original cited papers.