The limb bud is a structure formed early in limb development. As a result of interactions between the ectoderm and underlying mesoderm, formation occurs roughly around the fourth week of development as mesenchymal cells from the lateral plate mesoderm and the somites begin to proliferate to the point where they create a bulge under the ectodermal cells above. The limb bud remains active throughout much of limb development, and its signaling stimulates formation of another signaling center, the apical ectodermal ridge (AER) as well as formation of the zone of polarizing activity (ZPA) within the mesenchyme. The mesenchymal cells of the limb bud, which stimulate AER formation as well as maintain AER activity, determine what type of limb will form. ZPA signaling will establish polarity of the limb, as well as sustain proper AER activity.
Other articles related to "limb bud, limb, limbs":
... specified for each segment in the early limb bud and this population of cells expand out as the limb bud grows ... Cell division is seen throughout the limb bud ... FGF-releasing beads are able to rescue limb development when the AER is removed by preventing this cell death ...
... AER Maintains Limb Outgrowth through FGF secretion, Mesenchyme Cells Determine Identity These experiments reveal that the limb mesenchyme contains the necessary information concerning limb identity ... If an FGF bead is added in the AER’s place, normal limb development proceeds ... When an extra AER is added, two limbs form ...
... Later, FGF10 expression is restricted to the developing limb mesenchyme, where it is stabilized by WNT8C or WNT2B ... WNT3A = Acts as a middle man in the positive feedback loop between the AER and limb mesenchyme ... Shh = Secreted by the ZPA in the limb bud mesenchyme ...
Famous quotes containing the words bud and/or limb:
“Go, pretty child, and bear this flower
Unto thy little Saviour;
And tell Him, by that bud now blown,
He is the Rose of Sharon known.”
—Robert Herrick (15911674)
“I doubt that I would have taken so many leaps in my own writing or been as clear about my feminist and political commitments if I had not been anointed as early as I was. Some major form of recognition seems to have to mark a womans career for her to be able to go out on a limb without having her credentials questioned.”
—Ruth Behar (b. 1956)