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":
... Cells are 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 ...
... Later, FGF10 expression is restricted to the developing limb mesenchyme, where it is stabilized by WNT8C or WNT2B ... positive feedback loop between the AER and limb mesenchyme ... Shh = Secreted by the ZPA in the limb bud mesenchyme ...
... AER Maintains Limb Outgrowth through FGF secretion, Mesenchyme Cells Determine Identity These experiments reveal that the limb mesenchyme contains the necessary information ... If an FGF bead is added in the AER’s place, normal limb development proceeds ... When an extra AER is added, two limbs form ...
Famous quotes containing the words bud and/or limb:
“This bud of love by summers ripening breath
May prove a beauteous flower when next we meet.”
—William Shakespeare (15641616)
“... our great-grandmothers were prudes. The reason why they talked so much about their souls, I fancy, is that there was hardly a limb or a feature of the human body that they thought it proper to mention.”
—Katharine Fullerton Gerould (18791944)