Fig. 5

Continued requirement for zFmi1a during early segmentation stages: failure to elevate the neural keel. (A–H) 3-somite stage, (I, J, M–P) 7-somite stage, and (K and L) 10-somite stage. In lateral views, dorsal is to the right and in dorsal views, anterior is up. Marker genes are as indicated on the plates. (A–D) Convergence of paraxial and lateral mesoderm and neural plate is delayed in F1a-GPS1 morphants. Abbreviations: px; pax2.1, k; krox20. (B) Arrow indicates correct width of axial domain. (E–H) Convergence of the axial domain from F1a-GPS1 morphants subsequently becomes identical to controls (F1a-GPS1 morpholino but with four nucleotide changes). (E and F) Optical sections, dorsal is up; shh, sonic hedgehog. (J) Arrow indicates loss of posterior pax2.1 expression. (L) Arrow indicates loss of myoD expression within lateral somites. Representative embryo displaying both reduced and absent expression of myoD, embryo has been overstained to detect weak expression. Morphants displaying greatest impairment of convergence and extension exhibited complete absence of myoD in anterior somites. (M–P) Defective convergence of neuroepithelium disrupts morphogenesis of notochord; shh, sonic hedgehog. (O and P) optical sections; dorsal is to top, hashed lines mark the boundary between neural keel/plate and somitic domain.