Fig. 6. Impairment of tectal development in ntn mutant embryos. (A) Confocal optical section images of the tectum of Bodipyceramide stained wild-type (wt) and mutant (ntn) embryos at 28 hpf, 36 hpf and 40 hpf. An arrow indicates cell-free spaces. Arrowheads point large and round cells representing mitotically active cells. (B) TUNEL staining of coronal sections through the tectum of wild-type (wt) and mutant (ntn) embryos at 30 hpf, 36 hpf and 40 hpf. An arrow indicates TUNEL-positive cells. (C) Confocal composite images of immunostaining with anti-acetylated tubulin antibody of wild-type (wt) and mutant (ntn) embryos at 30 hpf, 36 hpf and 40 hpf. An arrow indicates the absence of tectal neuropil. (D) In situ hybridization of brn3b mRNA in wild-type (wt) and mutant (ntn) embryos at 48 hpf. Dorsolateral view. Arrows indicate the tectum. Scale bars: 50 µm in A,C; 100 µm in B,D.