An ectodermal thickening at the end of the forelimb bud in the developing embryo. [TFD][VHOG], Apical ectodermal ridge that is part of the pectoral fin bud.[TAO]

upper limb bud apical ectodermal ridge, wing AER, apical ectodermal ridge pectoral fin bud, wing apical ectodermal ridge, AER forelimb, apical ectodermal ridge forelimb

uberon

aer pectoral fin, apical ectodermal ridge pectoral fin, apical fold pectoral fin

Pectoral and pelvic fins are homologous to the tetrapod fore and hindlimb, respectively. (...) The zebrafish AER [apical ectodermal ridge] is an apical ectodermal thickening at the distal tip of the fin bud and consists of wedge-shaped cells of the basal stratum. The AER is observed only transiently, and from 36 hpf onwards the cells of this region form the apical fold (AF), which consists of a dorsal and a ventral layer of cylindrically-shaped ectodermal cells extending from the anterior to the posterior fin margin. Despite the change in shape, the AF still carries out the same functions as the AER. Indeed, although the AER receives its name from its characteristic shape, being composed of a pseudostratified ectoderm in the chicken and a polystratified ectoderm in the mouse, this independence of AER morphology from its function is also observed in tetrapods. The AF also expresses similar molecular markers to the tetrapod AER, suggesting that it fulfills similar functions in the fin as the AER does in tetrapod limbs.[well established][VHOG]

UBERON:0005421

• fin fold pectoral fin bud