The zone of polarizing activity (ZPA) is an area of mesenchyme that contains signals which instruct the developing limb bud to form along the anterior/posterior axis. Limb bud is undifferentiated mesenchyme enclosed by an ectoderm covering.

A-P patterning is established by the Zone of Polarizing Activity (ZPA) on the posterior side of the limb (i.e. the little finger side). Shh signaling from the ZPA specifically signals the formation of posterior elements. Loss of the ZPA therefore results in loss of posterior elements

1993年12月31日 · Retinoic acid, which can convert anterior limb bud tissue into tissue with polarizing activity, concomitantly induces Sonic hedgehog expression in the anterior limb bud. Implanting cells that express Sonic hedgehog into anterior limb buds is sufficient to cause ZPA-like limb duplications.

The ZPA was operationally defined in chick as the region of cells with the potential to act in posteriorization of limb tissues. Long after the discovery of the ZPA, it was found that shh expressing cells have polarizing activity, and shh expression in the chick wing maps specifically to the ZPA (Riddle et al., 1993).

1997年9月19日 · According to this model, ZPA cells secrete a morphogen which sets the identity of cells along the A/P limb axis. Cells near to the ZPA would receive a high concentration of the morphogen, and adopt posterior fates, while cells further from the ZPA would sense a lower morphogen concentration and adopt anterior fates.

AP patterning of distinct digit ‘identities’, initiated by ZPA signaling, is a major target of evolutionary functional adaptations and, being a bony structure readily appreciated in the fossil record, the limb has consequently become a preeminent model for evo-devo studies (Schneider and Shubin, 2013; Zuniga, 2015).

1993年12月31日 · The zone of polarizing activity (ZPA) is a region at the posterior margin of the limb bud that induces mirror-image duplications when grafted to the anterior of a second limb. We have isolated a vertebrate gene, Sonic hedgehog, related to the Drosophila segment polarity gene hedgehog, which is expre …

1993年12月31日 · Retinoic acid, which can convert anterior limb bud tissue into tissue with polarizing activity, concomitantly induces Sonic hedgehog expression in the anterior limb bud. Implanting cells that express Sonic hedgehog into anterior limb buds is sufficient to cause ZPA-like limb duplications.

2011年2月28日 · The zone of polarizing activity (ZPA) is defined as the region of the vertebrate limb that, upon transplantation to the anterior limb bud mesenchyme, results in the formation of ectopic digits (Saunders and Gasseling, 1968). In the early 1990s, cells located within the ZPA were found to express sonic hedgehog (Shh) (Riddle et al., 1993).

极化活动区（zpa）是肢体芽后缘的一个区域，当嫁接到第二个肢体的前部时会引起镜像重复。 我们已经分离出一个与果蝇节段极性基因刺猬有关的脊椎动物基因Sonic刺猬，该基因在ZPA和胚胎的其他区域中特别表达，能够在移植实验中使四肢极化。