Limb development Flashcards
what is the term for the region of the trunk able to form the limb bud
forelimb field
what is the term for the space inside the limb bud formed of mesenchymal cells
progress zone
what is the structure that controls the outgrowth of the limb along to proximal distal axis and forms a thickening of the limb bud ectoderm
apical ectodermal ridge (AER)
what does the AER express
Fgf8
what structure specifies the anterior posterior axis of the limb
the zone of polarising activity (ZPA)
what does the ZPA express
Shh
what are somites
cells of the paraxial mesoderm originating from the lateral sides of the notochord which specify the limb position and specify the limb field
where is fgf8 expressed before limb outgrowth
anterior & middle posterior of embryo
what is RAs role in limb formation
specifies forelimb field - inhibited by Fgf8
what does Fgf10 do?
induces limb bud formation
what are the TFs that specific either upper or lower limb development
Tbx5 - upper limb
Tbx4 - lower limb
how does Tbx5 control Fgf10 expressin
via a positive feedback loop which also involves Wnt2b, sufficient fgf10 results in mesenchymal cell proliferation
how is EMT induced
Tbx5
a 2nd feedback loop exists in the ectoderm what factors are involved?
fgf10, fgf8 and wnt3a
what factor contributes to outgrowth if the hindlimb
Islet1
