… of Shh in patterning the chick limb. Our results are most consistent with a model in which
the concentration of Shh is the primary determinant of AP polarity in the limb. Our results also …

… We have no evidence that the SHH effect we observe on muscle lineage in the chick limb
bud is mediated by the inhibition of the PKA activity, but it seems plausible that this occurs. …

… a measure of the distance that Sonic hedgehog diffuses and directly acts. On this basis, we
find that Sonic hedgehog directly acts as a signal over only the posterior third of the limb bud. …

… (A) Stage 20 chick limb buds were injected with Sonic hedgehog expressing retrovirus at
the anterior margin underneath the AER and harvested 16 hr later. GLI expression is induced …

… of chick limb buds, and therefore lacks polarizing activity. We propose that a prepattern exists
in the limb field for the three axes of the emerging limb bud as well as specific limb skeletal …

… Sonic hedgehog (Shh) is expressed in the polarizing region (or zone of polarizing activity),
a small group of mesenchyme cells at the posterior margin of the vertebrate limb … chick limbs …

… specify the proximal part of the limb24 and Cliff Tabin discovered … limb is Sonic hedgehog
(Shh).11 Here we review the evidence that Shh is the polarizing region morphogen in the chick …

… Development of the musculature in chick limbs involves … patterning is localised within the
limb mesenchyme and not in the … The anterior-posterior axis of the limb is specified by a group …

… region, at the posterior of the vertebrate limb bud, is pivotal in … Increasing PKA levels in chick
limb development using … signaling, was induced in anterior limb bud cells resulting in extra …

… for applying Sonic hedgehog (Shh) to developing chick limbs. The Sonic hedgehog gene is
expressed in the polarizing region, a signaling region at the posterior margin of the limb bud …