Overexpression of FGF in the DMZ, but not the VMZ, eliminates the anterior hemangioblast program. Embryos at the 4-cell stage were injected with 400 fg eFGF mRNA either into the DMZ (B,D,F,N,P,R,T) or the VMZ (H,J,L). Control embryos (A,C,E,G,I,K,M,O,Q,S) were water injected. Embryos were grown to stage 18/19 and then probed by in situ hybridization for Scl, Fli1, Mpo, Runx1, MyoD, or Nkx2.5. Probes used are indicated in the bottom left hand corner, and numbers of embryos probed are indicated in the bottom right-hand corner of each box. Panels M,N and O,P are anterior-ventral and dorsal views, respectively, of the same embryo probed for Runx1. Panels Q and R show dorsal views for left-hand embryos and anterior-ventral views for right hand embryos. All other embryos show anterior-ventral views.