Increased cell death during neurogenesis in GDF6 depleted embryos. (A) Stage 20 embryo injected with 20 ng GDF6 MO shows a patch of TUNEL at the anterior region of the injected side (i). (B) Stage 22 embryo injected with 20 ng GDF6 MO showing TUNEL positive cells near the midline at the anterior region of the injected side (i). (C) Stage 22 embryo injected with 50 ng GDF6 MO showing more extensive TUNEL staining which extends along the length of the injected side (i). There is an obvious reduction in physical size on the injected side. (D) Stage 27 embryo injected with 50 ng GDF6 MO showing dark concentrated TUNEL staining in the brain and retina on the injected side (i). This embryo is also curled towards the injected side. (E) Graphical representation of the percent embryos with increased TUNEL staining on the injected side at stage 20–24 and stage 27. (F, G) The GDF6 MO (25 ng) injected side (F) and uninjected side (G) of a stage 27 embryo, showing heavy TUNEL staining in the retina and brain.