Fig. 9. Schematic representation of the fate of MH precursor cells (green, territory delimited by the green stars) in wild-type embryos (A) or in the absence of Fgf8 (B) or Pax2.1 (C) activities (interpreted from Fig. 8, and data not shown). In each drawing, the thin horizontal black line delimits the alar/basal boundary; gene expressions are color coded. Pink arrows delimit the population of anterior MH cells that acquires a pax6.1-positive identity in ace and blue arrows point to the extension of fgfr3 expression in noi. Note the striking differences in the alternative identities taken by MH precursors depending on the mutant context.