Mesoderm induction and mesoderm-inducing factors in early amphibian development.

Introduction Experimental embryology and mesoderm induction The three-signal model of mesoderm formation Mesoderm-inducing factors Mesoderm-inducing factors as growth factors Xenopus embryos contain TGF-fi-like molecules Xenopus embryos contain FGF Elimination of inducing factors from Xenopus embryos Mesoderm-inducing factors and pattern formation Thresholds Mesoderm induction, gastrulation and developmental clocks Modulation of the effects of mesoderm-inducing factors: inhibitors and further cell-cell interactions Conclusions