Fig. 2. charon expression in zebrafish. In situ hybridization analysis revealed that charon expression was initiated around 12 hpf at the 6-somite stage in the tailbud (A,B). charon expression became more obvious at 14 hpf (10-somite stage) (C,D). The charon transcripts were observed in the posterior half of the flanking domain of Kupffer's vesicle in a horseshoe shape (D, refer to E,F). The expression continued through 15 hpf to 18 hpf in the same tissue (16 hpf, 14-somite stage, G,H). The expression pattern of charon mRNA in Fugu (I,J) and flounder (K,L, refer to M) was very similar to that in zebrafish. The charon transcripts were not detected in any other domain throughout embryogenesis. There was no obvious L/R bias in the strength of charon expression in the majority of embryos. (A,C,E,G,I,K,M) Lateral views. (B,D,F,H,J,L) Vegetal pole views of the tailbud region. (E,F,M) Control non-stained embryos. Arrowheads indicate the position of Kupffer's vesicle.