Fibroblast growth factors induce additional limb development from the flank of chick embryos.
Fibroblast growth factors (FGFs) act as signals in the developing limb and can maintain proliferation of limb bud mesenchyme cells. Remarkably, beads soaked in FGF-1, FGF-2, or FGF-4 and placed in the presumptive flank of chick embryos induce formation of ectopic limb buds, which can develop into complete limbs. The entire flank can produce additional limbs, but generally wings are formed anteriorly and legs posteriorly. FGF application activates Sonic hedgehog in cells with polarizing potential to make a discrete polarizing region. Hoxd-13 is also expressed in the ectopic bud, and an apical ectodermal ridge forms. A limb bud is thus established that can generate the appropriate signals to develop into a complete limb. The additional limbs have reversed polarity. This can be explained by the distribution of cells in the flank with potential polarizing activity. The results suggest that local production of an FGF may initiate limb development.
Cohn
M J
MJ
Department of Anatomy and Developmental Biology, University College and Middlesex School of Medicine, London, England.
Izpisúa-Belmonte
J C
JC
Abud
H
H
Heath
J K
JK
Tickle
C
C
D000818:Animals; D002642:Chick Embryo; D004268:DNA-Binding Proteins / Q000096:biosynthesis; D004627:Embryonic Induction / Q000187:drug effects*; D005121:Extremities / Q000196:embryology*; D005346:Fibroblast Growth Factors / Q000494:pharmacology*; D053823:Hedgehog Proteins; D018398:Homeodomain Proteins; D008648:Mesoderm / Q000166:cytology / Q000187:drug effects*; D008863:Microspheres; D009024:Morphogenesis / Q000187:drug effects; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000032:analysis; D015534:Trans-Activators; D014157:Transcription Factors
D004268:DNA-Binding Proteins; D053823:Hedgehog Proteins; D018398:Homeodomain Proteins; D012333:RNA, Messenger; D015534:Trans-Activators; D014157:Transcription Factors; D005346:Fibroblast Growth Factors