... expression encompasses the zone of polarizing activity in the posterior region, where it has been shown to be necessary and sufficient to induce the expression of the morphogen sonic hedgehog. Misexpression of dHAND in the anterior compartment of the limb bud induces ectopic expression of sonic hedgehog...

...Jeroen Charité; David G. McFadden; Eric N. Olson ABSTRACT Limb outgrowth and patterning of skeletal elements are dependent on complex tissue interactions involving the zone of polarizing activity (ZPA) in the posterior region of the limb bud and the apical ectodermal ridge. The peptide morphogen...

... © 2000 by Company of Biologists 2000 dHAND Limb development Pattern formation RCAS-infection Zone of polarizing activity Chick embryo Mouse embryo Shh pathway The development of the vertebrate limb has proved to be a fruitful model for analyzing developmental processes...

... on several interacting signaling centers; one of these, the zone of polarizing activity (ZPA), comprises a group of mesenchymal cells along the posterior aspect of the limb bud that express sonic hedgehog ( Shh ) and plays a key role in patterning the anterior-posterior (AP) axis. The mechanisms by which...

... that restricts ZPA formation to the posterior limb bud mesenchyme. * Author for correspondence 25 07 1997 © 1997 by Company of Biologists 1997 polydactyly Zone of Polarizing Activity gastroschesis mouse Alx4 limb Sonic hedgehog In the vertebrate limb, patterning...

...Hui-Chen Lu; Jean-Pierre Revelli; Lisa Goering; Christina Thaller; Gregor Eichele ABSTRACT We show that retinoid receptor antagonists applied to the presumptive wing region block the formation of a zone of polarizing activity (ZPA). This suggests a direct relationship between retinoid signaling...

...Jill Helms; Christina Thaller; Gregor Eichele ABSTRACT Local application of all- trans -retinoic acid (RA) to the anterior margin of chick limb buds results in pattern duplications reminescent of those that develop after grafting cells from the zone of polarizing activity (ZPA). RA may act directly...

... plate notochord zone of polarizing activity The induction and patterning of many vertebrate tissues depends on signals that derive from restricted groups of cells in the early embryo. The induction and anteroposterior (A-P) patterning of neural ectoderm in amphibia is controlled by signals...

...R. Victoria Stirling; Dennis Summerbell The effect of alteration of limb pattern upon motor axon guidance has been investigated in chick embryos. Following grafting of the zone of polarizing activity (ZPA) into the anterior margin of the early limb bud, limbs develop with forearms duplicated about...

... activity apical ectodermal ridge diffusible morphogen Two regions of the embryonic chick wing bud, the apical ectodermal ridge (AER) and the posterior zone of polarizing activity (ZPA), have been shown to alter the rate and pattern of growth during limb development in vivo ( Saunders, 1948...

... of a mirror-image limb duplication. This positional signalling region ( Wolpert, 1969 ) or organizer ( Spemann, 1938 ) was originally discovered by Saunders & Gasseling (1968) and subsequently named the Zone of Polarizing Activity (ZPA). It is a unique region with properties different in kind from any...

...K. M. Bell; J. C. McLachlan ABSTRACT Two regions of the chick limb bud — the apical ectodermal ridge and the zone of polarizing activity — have been shown to influence cell division and pattern formation during normal development and following surgical manipulation. In this study, using a simple...