Fig. 8. bts1 expression during somitogenesis distinguishes Pax2.1 and Fgf8 functions. (A-D) Comparison of bts1 and pax2.1 expression in wild-type (left) or ace mutant (right) embryos at the 13-somite stage. The MHD is indicated by the arrowhead. bts1 expression is unperturbed in ace (B), when most pax2.1 expression has already been eliminated (D). (A,B) ace embryos identified by their reduced otic vesicles, which also express bts1 (not visible on the figure). (E-H) Comparison of bts1 and fgf8 expression in wild-type (left) or noi mutant (right) embryos at the 10-somite stage. bts1 expression is strongly diminished following the same schedule as other MHD markers (e.g. fgf8). lim5 expression (red) is unperturbed.