part of part of capable of capable of developmentally induced by developmentally induced by produces produces regulation of mesenchymal cell proliferation negative regulation of cartilage development fibroblast growth factor 8 ectoderm embryonic structure mesenchyme apical ectodermal ridge http://upload.wikimedia.org/wikipedia/commons/5/56/Limbbuddiagram.jpg AER EMAPA:32744 XAO:0004121 UBERON:0004356 crista ectodermalis apicalis NCIT:C34109 Distal ectodermal thickening which forms along the anterior-posterior limb axis. Signaling from this region influences proximal-distal patterning of the limb. Structure is missing in some lineages (salamanders, Eleutherodactylus coqui) however morphologically their indistinct distal ectoderm may still be involved in signaling.[AAO] ZFA:0001702 UMLS:C1516037 note that media, dorsal fins etc have AERs. AAO:0010760 Multilayered ectodermal region at the distal tip of a limb or fin bud necessary for the proper development of the underlying mesenchyme[MP,modified]. Along with the zone of polarizing activity, it is a crucial organizing region during limb development[WP]. TAO:0002146 The AER of tetrapods regresses after specification of skeletal progenitors, the AER of teleosts form an elongating fin fold relationship loss: subclass proliferative region (TAO:0000098)[TAO] Wikipedia:Apical_ectodermal_ridge Proliferative region that is part of the developing fin fold or fin.[TAO] apical epidermal ridge maintaining mesenchyme in plastic proliferating state; maintaining expression of A-P axis genes; interacting with D-V proteins. Genes: AER induced by Fgf10 in mesenchyme. AER secretes Fgf8, which stimulates mitosis in the mesenchyme causing Fgf10 production - positive feedback loop paired limb/fin bud