recent studies indicate that one of the major functions of the apical ectodermal ridge ( aer ) of the embryonic chick limb bud is to maintain mesenchymal cells directly subjacent to it ( i.e . cells extending 0.4-0.5 mm from the aer ) , in a labile , undifferentiated condition , and that when mesenchymal cells are freed from the aer 's influence either artificially or as a result of normal polarized proximal to distal limb outgrowth , they are freed to commence cyto-differentiation .
C0007634
cells
C0007589
differentiation