Injection of iron dextran rescues the anemia in arhgef3 MO-injected embryos. (A-D) O-Dianisidine staining of blood collected by cardiac puncture from control and arhgef3 MO-injected embryos at 48 and 72 hpf. Erythrocytes from the arhgef3 MO-injected embryos (B,D) have less hemoglobin and are smaller compared with erythrocytes from control embryos (A,C). (E) Injection of iron dextran (Fe) at the 1-cell stage deposits a supply of usable iron, which is distributed to all cells of the developing embryos during subsequent cell divisions, including erythroid cells. (F-L) Whereas no difference in hemoglobin staining (indicated by black arrows) was detected in the control embryos injected with Fe (H) compared with noninjected controls (F), arhgef3 MO-injected embryos supplemented with Fe (I) showed a significant recovery in hemoglobin levels compared with the ones without supplementation (G) at 30 hpf. (I) Inset shows higher magnification view of the boxed area (black arrow shows accumulated erythrocytes stained with o-Dianisidine). Erythrocytes from arhgef3-depleted embryos supplemented with Fe showed wild-type structure and restored hemoglobin levels at 48 hpf (L) compared with arhgef3 MO-injected embryos (K).