13-P057 Allelic imbalance of Shh expression and polydactyly are linked to a SNP in the ZRS region of Lmbr1 in Silkie chickens

In the mouse, however, it has been demonstrated that the two most posterior of the five digits are derived entirely from the polarizing region by proliferation without the requirement of Shh diffusion. To understand the contribution and significance that polarizing region cell proliferation has in forming different digit patterns, we grafted polarizing regions from a transgenic chicken line stably expressing Green Fluorescent Protein (GFP) into normal wing buds (three digits), or leg buds (four digits). We will describe how these fate-maps behave when either Shh signalling is dampened, or proliferation is inhibited. We will present a model outlining our findings, highlighting the evolutionary implications.