Fig. 7. A pathway for myogenic induction. A molecular pathway depicting the role of eFGF signalling in the induction of XmyoD in response to the mesoderm inducing factor. A maternal factor such as VegT induces the expression of a TGFß family member(s) which act as the endogenous mesoderm inducing factor; this is likely a nodal related factor (Xnr1 and/or Xnr2). We mimic the endogenous mesoderm inducing factor with activin in our experiments and show that it induces the expression of eFGF directly. eFGF protein directly induces the expression of XmyoD, possibly acting through inhibition of a repressor. XmyoD is crucial in the specification of the myogenic cell lineage.