crs embryos are anemic despite normal blood specification. (A-F) Whole-mount o-dianisidine stain for hemoglobin in wild-type (WT) (A,C,E) and mutant (-/-) (B,D,F) embryos at 33 hpf (A-B) and 48 hpf (C-F). Arrows (C-D) indicate blood flow in the tail vessels. Blood flow over the yolk sac is bracketed (C-D) and shown higher magnification (E-Fi). A few o-dianisidine–positive cells over the yolk sac in mutant animals (bracket in Fi) are further magnified and indicated by an arrowhead (Fii). (G-L) Whole-mount in situ hybridization for gata1 (G-J) and β_e3 globin (L) at 33 hpf (G,H,K,L) and 48 hpf (I-J) in wild-type (G,I-K) and mutant (H,J,L) embryos.