Fig. 2. Double whole-mount in situ hybridisation shows that at the level of sinus rhomboidalis the expression pattern of the cycling genes is not coincident. (A-C) Double in situ hybridisation in six-somite stage embryos with hairy1 (blue staining) and hairy2 (red staining) RNA probes. The expression domains of these genes are distinct, as evidenced by the caudal extension of the hairy2 domain in relation to hairy1. (D-F) Double in situ hybridisation with hairy1 (blue staining) and lunatic fringe (red staining) RNA probes. At the level of sinus rhomboidalis, we observe that, in some embryos, the expression pattern of lunatic fringe is different from hairy1, extending more posteriorly (see D). (G-I) Double in situ hybridisation with lunatic fringe (blue staining) and hairy2 (red staining) RNA probes. The expression pattern of hairy2 protrudes more caudally than that of lunatic fringe (see G-I). At the level of PSM, the expression domains of the three genes coincide at its anterior border, although at its caudal limit they are not completely coincident. Rostral is towards the top. Scale bar: 300 µm