Fig. 8. Function of eng2/eng3 and fgf8 in AP patterning of the anterior neural plate. Pax6.1 (blue) demarcates the forebrain and hindbrain, whereas expression of eng2/eng3 (yellow) and fgf8 (red) can be observed in the midbrain/MHB organizer territory (A). Eng2/Eng3 displays the cell-autonomous signal maintaining midbrain fate, whereas Fgf8 acts non-autonomous in the midbrain territory visualized by red arrows. (B) Loss of Eng2/Eng3 causes a posterior shift of the DMB (blue arrow). Fgf8 expression is unaffected at least until 10 ss, suggesting a partial repression of the forebrain expansion. Loss of both signal Eng2/Eng3 and Fgf8 causes in a loss of midbrain identity and in a fusion of forebrain and hindbrain domain (C). Only a dorsal patch of cells remains free of pax6.1 expression. DMB, diencephalic-mesencephalic boundary.