Fig. 6

Dorsal view of myoD RNA (blue staining) and Ntl antibody staining (brown nuclear staining) at (A-G) tailbud stage and (H-M) 15- somite stage of (A,H) wild-type, (B,I) flh^tk241, (C,J) mom^th211, (D,K) ntl^tc41, (E) ntlb160, (F) ntltb244e, (L) ntl^ts260 and (G,M) doc^tt258 embryos. (A) In wild type at the tailbud stage myoD expression is restricted to a line of cells left and right of the notochord. (B,C) The gap between the two stripes is filled with myoD expressing cells in (B) flh^tk241 and (C) mom^th211 embryos. ntl expression is detectable only in the tailbud and sometimes in a few cells anteriorly, which do not express myoD (C). (D) Strongly reduced myoD expression a greater distance from the midline is detectable in embryos with the strong allele, ntl^tc41(arrows). myoD expression at the 15-somite stage in (H) wild type is expressed in the adaxial cells and in the posterior part of the somites. In (I) flh^tk241 embryos and (J) mom^th211 embryos myoD expression in the adaxial cells is not maintained. (K) In embryos with the strong allele, ntl^tc41, somites are separated by a big gap of nonexpressing cells, whereas the 15th somite is fused in the midline (arrow). (L) In embryos with the weak allele, ntl^ts260, adaxial cells next to ntl-expressing cells express myoD at a higher level than the somites on the opposite side. (M) In doc^tt258 embryos adaxial expression in anterior regions is reduced and closer together.