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. 2023 Jan 9;10:1091629. doi: 10.3389/fcell.2022.1091629

FIGURE 3.

FIGURE 3

Somitic mesoderm convergent extension in necessary for neural tube closure. (A) Transverse cross section a representative Wee2 morphant stage 16 embryo. Yellow double arrowhead: somite dorsoventral (D/V) length. Purple double arrowhead: mediolateral (M/L) somite length. Asterisk indicated the Wee2 morphant side. Red arrows: hinge point at the neural plate side overlying normal somitic mesoderm. (D) dorsal. V, ventral. (A’) Zoomed images of control and Wee2 morphant somitic mesoderm. Scale bar:100 μm (B) Quantification of somitic mesoderm convergent extension index in control Wee2 morphant somitic mesoderm. Two-sided paired Student’s t-test; ****p < .0001; n = 14 embryos. (C) Stills showing the dorsal side of the embryo from a time lapse recording of a neurula embryo with unilateral Wee2 morphant somitic mesoderm. Asterisk: Wee2 morphant side. Red dotted line: neural plate midline. Green arrowheads: Neural plate boundary at the side overlying control somitic mesoderm. Orange arrowheads: Neural plate boundary at the side overlying Wee2 morphant somitic mesoderm. NTC is delayed at the neural plate side overlying Wee2 morphant somitic mesoderm (purple arrowheads). Scale bar: 100 μm (D) Quantification of neural plate mediolateral width extension. Neural plate is wider when the underlying somitic mesoderm is targeted with Wee2 morpholino. Two-sided paired Student’s t-test; ****p < .0001; n = 32 embryos. (E) Quantification of neural plate width over time. 3 regions along the anteroposterior axis of a neurula embryo were followed over time. Neural plate width at the side overlying Wee2 morphant somitic mesoderm remains wider as neurulation progresses. (F) Dorsal view from a tracked time lapse recording for 1 h time period, showing surface ectoderm boundary cells movement during neural tube closure. Asterisk: Wee2 morphant somitic mesoderm side. (A) Anterior; P: Posterior. Scale bar: 100 μm (G) Quantification of surface ectoderm boundary cells velocity as a proxy for neural plate hinge point movement. The velocity of surface ectoderm boundary cells is significantly reduced when somitic mesoderm convergent extension is impaired. Two-sided unpaired Student’s t-test; ****p < .0001; mean ± SEM; n = 15 cells.