Fig. 1

Disruption of the segmentation clock in tbx6, her1;her7 and her1;her7;tbx6 mutants.

(A?D?) In situ hybridization for segmentation clock marker her7. (B and B') her7 oscillates in the posterior PSM of tbx6^?/?, but does not oscillate in her1^?/?;her7^?/? (C and C´) or her1^?/?;her7^?/?;tbx6^?/? (D and D`). (E?H) In situ hybridization for segmental output marker mespb. mespb is not expressed in tbx6^?/? (F) or her1^?/?;her7^?/?;tbx6^?/? (H), but is weakly expressed in her1^?/?;her7^?/?, albeit not in segmental stripes (G). (I?L?) Somite boundaries in the paraxial mesoderm. In tbx6^?/? (J), her1^?/?;her7^?/? (K) and her1^?/?;her7^?/?;tbx6^?/? (L) mutants, boundaries lose periodic order. (M?P?) Spatial distribution of muscle pioneers marked by in situ hybridization with en2a. In tbx6^?/? (N), her1^?/?;her7^?/? (O) and her1^?/?;her7^?/?;tbx6^?/? (P) muscle pioneers lose segmental pattern. A-H? are dorsal views of 13.5 hpf (10 somites) embryos, I-P' are lateral views of 18?19.5 hpf (18?20 somites) embryos. a ? anterior, p ? posterior. Scale bar in A is 100 µm and applies to A-G. Scale bar in I is 150 µm, applies to I-L and in I? is 100 µm, applies to I?-L?. Scale bars in M and M? are 150 µm and 100 µm respectively, and apply to M-P and M?-P? respectively.