Fig. 2. Initial brain ventricle formation is normal in the absence of circulation. Living, anesthetized embryos from a heterozygous cross of the silent heart (sih) mutant were injected with Texas Red-dextran. At 24 and 27 hpf, the pattern of ventricle formation is identical in wild type (A,C) and sih mutant (B,D). At 36 hpf, the volume of brain ventricles is smaller in sih (F) than in wild type (E). (A-D) Dorsal views, (E,F) side views, anterior to left. Scale bar: 50 µm.