An area of mesenchymal cells that contains signals which instruct the developing limb or fin bud to form along the anterior/posterior axis. [ http://orcid.org/0000-0002-6601-2165 http://en.wikipedia.org/wiki/Zone_of_polarizing_activity ]
Synonyms: ZPA
Term information
pheno_slim
Sonic hedgehog (Shh) produced by ZPA represents the key mediator of the polarizing activity that regulates patterning of the limb/fin along the anterio-posterior (A-P) axis[MP:0012528]
Morphologically indistinct signaling region found in the posterior portion of the limb bud. Associated with anterior-posterior patterning of the digits.[AAO]