Fig. 4

Fig. 4 Morphology of eye and brain of living embryos between 24 and 37 hpf. (A-C) Comparison of control (uninjected) and injected embryos at 24 hpf (dorsal view). In the control embryo (A), the two eyes are separated by the neural tube at the midline. In injected embryos (B, C) the eyes have expanded across the midline (arrowhead), resulting in deletion of forebrain (telencephalon). In (B), the eyes have fused with the diencephalon (arrows) proximal and caudal to the optic stalks. In (C), the eyes have fused at the midline, but also remain attached to the diencephalon through the optic stalks, in the region of the hypothalamus. The ventricular space in the midbrain is enlarged in this embryo. (D-F) Comparison of control, injected, and cyclops embryos at 37 hpf (frontal view). In the injected embryo (E), the expanded eyes have obliterated the telencephalon, but the hypothalamus is present. In contrast, the cyclops embryo (F) lacks a hypothalamus but retains the telencephalon. Embryos were injected with 300 pg rx2ΔRx (B, C) or 1 ng rx2ΔC′ (E) RNA. d, diencephalon; e, eye; h, hypothalamus; m, mesencephalon; os, optic stalks; t, telencephalon. Scale bars: 100 μM.