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]. [ MP:0001676 http://en.wikipedia.org/wiki/Apical_ectodermal_ridge ]

Synonyms: apical epidermal ridge

This is just here as a test because I lose it