title: Forming and interpreting gradients in the early Xenopus embryo.
abstract: The amphibian embryo provides a powerful model system to study morphogen gradients because of the ease with which it is possible to manipulate the early embryo. In particular, it is possible to introduce exogenous sources of morphogen, to follow the progression of the signal, to monitor the cellular response to induction, and to up- or down-regulate molecules that are involved in all aspects of long-range signaling. In this article, I discuss the evidence that gradients exist in the early amphibian embryo, the way in which morphogens might traverse a field of cells, and the way in which different concentrations of morphogens might be interpreted to activate the expression of different genes.
authors.affiliation: National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA. jim.smith@nimr.mrc.ac.uk
authors.forename: James C
authors.initials: JC
authors.lastname: Smith
mesh_terms: D000818:Animals; D019521:Body Patterning; D015509:Developmental Biology / Q000379:methods; D018507:Gene Expression Regulation, Developmental; D008648:Mesoderm; D008954:Models, Biological; D009024:Morphogenesis / Q000502:physiology*; D015398:Signal Transduction; D013997:Time Factors; D016212:Transforming Growth Factor beta / Q000378:metabolism; D014982:Xenopus laevis / Q000196:embryology* / Q000378:metabolism*
chemical_list: D016212:Transforming Growth Factor beta