part_of part of part of develops_from develops from develops from pelvic appendage bud ectoderm apical ectodermal ridge pelvic appendage bud pelvic appendage apical ectodermal ridge EHDAA2:0003194 VHOG:0001066 ZFA:0001385 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] EMAPA:16892 uberon apical ectodermal ridge pelvic fin bud AER hindlimb An apical ectodermal ridge that is part of a pelvic appendage bud. TAO:0001385 An ectodermal thickening at the end of the hindlimb bud in the developing embryo. [TFD][VHOG] apical ectodermal ridge hind limb leg AER EFO:0003681 UBERON:0005422 lower lmb bud apical ectodermal ridge apical ectodermal ridge hindlimb Apical ectodermal ridge that is part of the pelvic fin bud.[TAO]