Fig. 7

Convergence and extension of the neural axis is defective in zygotic maternal dominant (ZMD) heterozygotes. A,B: Wild-type (WT, A) and severely affected (B) ZMD ava^-/+ sibling embryos at 10-somite stage; side view; white arrowheads demarcate the head to tail distance of the embryo. A′,B′: Dorsal view focused deep, showing the neural and somitic tissue in optical cross-section. A′,B′: Dorsal view focused shallowly, showing the width of the neural (arrows) and somitic (arrowheads) tissue along the mediolateral axis. A′,B′: Outline of the notochord (n), neural keel (nt), and somites (s), as traced from view in orientation (A′,B′), and of the eye (e), as traced from view in orientation A and B. C: Expression of N-cadherin (cdh2), in wild-type (C) and ZMD hab^-/+ (C′) embryos, 10-somite stage, dorsal view. Arrows indicate width of the neural tube and arrowheads width of somitic mesoderm. White arrowhead points out the gap in the midline of the neural tube. D,E: Expression of deltaA in wild-type (D) and ZMD hab^-/+ (E) embryos, 10-somite stage, dorsal view. Arrow indicates an extra row of cells in the midline of the neural tube, and the arrowhead points out the gap in the midline of the neural tube. D′-E′: Transverse cross-sections as indicated for wild-type (D′,D′′ and ZMD hab^-/+ (E′,E′′,E′′′). Outlines below the cross-sections demarcate the boundaries of deltaA staining in each neural cross-section. For reference, the dorsal detached cells and notochord, which do not express deltaA, are also outlined. F,G: Anti-acetylated tubulin staining (&alpha AT), in wild-type (F) and ZMD hab^-/+ (G) embryos, 24 hr, dorsal view. Arrows indicate extra rows of cells in the midline of the neural tube.