... does not impair limb outgrowth. Furthermore, we distinguish two distinct phases of limb development: a Tbx5 -dependent limb initiation phase, followed by a Tbx5 -independent limb outgrowth phase. In humans, mutations in the T-box transcription factor TBX5 are associated with the dominant disorder Holt...

...Marat Gorivodsky; Peter Lonai The epithelial b variant of Fgfr2 is active in the entire surface ectoderm of the early embryo, and later in the limb ectoderm and AER,where it is required for limb outgrowth. As limb buds do not form in the absence of Fgfr2, we used chimera analysis to investigate...

... streak and tailbud cells (see above). In our model for limb outgrowth, signals from the AER specify limb progenitor cells through a Wnt5a -independent mechanism. Wnt5a subsequently functions in the progress zone to regulate the proliferation of these limb progenitor cells in a fashion analagous...

..., these functions appear to be performed by two separate proteins. Lmx-1 is necessary and sufficient to specify dorsal identity and Lhx2 regulates limb outgrowth. Our results suggest that Lhx2 is closer to apterous than Lmx-1 , yet, in vertebrates, Lhx2 does not specify dorsal cell fate. This implies...

... factors in limb outgrowth, we have examined their effects on the in vitro morphogen-esis of limb buds of the amelic mutant chick embryos wingless ( wl ) and limbless ( ll ). Limb buds of wl and ll mutant embryos form at the proper time in development, but fail to undergo further outgrowth and subsequently...