Abstract
Two broad classes of models have been proposed to explain the patterning of the proximal-distal axis of the vertebrate limb (from the shoulder to the digit tips). Differentiating between them, we demonstrate that early limb mesenchyme in the chick is initially maintained in a state capable of generating all limb segments through exposure to a combination of proximal and distal signals. As the limb bud grows, the proximal limb is established through continued exposure to flank-derived signal(s), whereas the developmental program determining the medial and distal segments is initiated in domains that grow beyond proximal influence. In addition, the system we have developed, combining in vitro and in vivo culture, opens the door to a new level of analysis of patterning mechanisms in the limb.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Body Patterning*
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Cell Proliferation
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Cells, Cultured
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Chick Embryo
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Chondrogenesis
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Culture Media
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Extremities / embryology*
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Fibroblast Growth Factors / metabolism
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Fibroblast Growth Factors / pharmacology
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Gene Expression Regulation, Developmental
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Homeodomain Proteins / genetics
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Homeodomain Proteins / metabolism
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Limb Buds / cytology
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Limb Buds / embryology*
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Limb Buds / metabolism
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Mesoderm / cytology
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Mesoderm / embryology
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Mesoderm / metabolism
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Myeloid Ecotropic Viral Integration Site 1 Protein
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Neoplasm Proteins / genetics
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Neoplasm Proteins / metabolism
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Signal Transduction
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Tretinoin / metabolism
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Tretinoin / pharmacology
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Wnt Proteins / metabolism
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Wnt Proteins / pharmacology
Substances
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Culture Media
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Homeodomain Proteins
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Myeloid Ecotropic Viral Integration Site 1 Protein
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Neoplasm Proteins
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Wnt Proteins
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Tretinoin
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Fibroblast Growth Factors