Fig. 9. A model of MHD induction incorporating Bts1 function. Evidence in all vertebrates suggest that the expression of early MHD markers (her5, pax2.1, wnt1 and fgf8) (green) is established by following independent pathways. Bts1 (red) is a selective inducer of pax2.1 expression, and its own expression depends on Fgf8 signalling (blue). Other factors regulating bts1 expression might include Wnt molecules. In turn, Pax2.1 induces eng3 and pax5. Bts1 might also directly regulate the expressions of eng3 and pax5 (red arrows).
