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. 2020 Oct 26;9:e60234. doi: 10.7554/eLife.60234

Figure 5. IFT-A mutants display a failure of patterned apical remodeling.

(A) Schematic of midbrain regions analyzed in (B) (blue boxes) and (F) (yellow boxes). (B) Lateral and midline cells labeled with ZO1 are color-coded by apical area in wild-type littermate control (WT) and Ift122 mutant embryos. (C–E) Apical area distributions (C,D) and average apical cell area (E). Lateral measurements are reproduced from Figure 4J. (F) Contiguous 20 μm wide regions spanning the mediolateral axis from the midline to the lateral margins of the midbrain neural plate. Cells are labeled with ZO1 and color-coded by apical area. (G,H) Apical cell area plotted by distance from the midline. (I,J) Average cell height in midline and lateral cells (I) measured in transverse sections of the cranial neural plate (J). Phalloidin and laminin show apical and basal surfaces, respectively. A single value was obtained for each embryo and the mean ± SD between embryos is shown, n = 3–4 embryos/genotype, *p<0.05, **p<0.01 (one-way ANOVA test). See Supplementary file 1 for n and p values. Embryos are anterior up, 7 somites (B–H) or apical up, 12 somites (I,J). Bars, 20 μm.

Figure 5.

Figure 5—figure supplement 1. The convex to concave transition is defective in Ift122 and Ttc21b mutants.

Figure 5—figure supplement 1.

(A) Transverse sections of a Ttc21b mutant and a wild-type littermate control (WT) at eight somites. Phalloidin and laminin label the apical and basal surfaces of the neuroepithelium, respectively. DAPI (white) shows the nuclei. (B) Midline cells are significantly shorter than lateral cells in WT controls at eight somites. This difference is eliminated in Ttc21b mutants. (C–F) The ratio of the apical span to the basal span of the neuroepithelium is increased in Ttc21b mutants at mid-elevation (8–9 somites) (C,D) and in Ift122 mutants at late elevation (12 somites) (E,F). Apical and basal spans were measured from one border to the other, encompassing midline and lateral cells. A single value was obtained for each embryo and the mean ± SD between embryos is shown, n = 3 embryos/genotype, *p<0.05, **p<0.01 (one-way ANOVA test in B, Welch’s t-test in C–F). See Supplementary file 1 for n and p values. Apical up. Bars, 20 μm.