Tnc is required for hindgut lumen diameter expansion.

<p>(A–C) Wild type embryos were labelled for Crb (magenta) and Dg (green) to visualize the apical and basal surfaces of the hindgut epithelium. Arrows point to anterior and posterior Li borders, and stippled lines mark outer tube diameter. Crb-staining only is shown in A′–C′. At stage 13 (A, lateral view) the hindgut is narrow with an anterior hook pointing ventral. By stage 14, (B, dorsal view) the anterior hook has turned right and Crb-expressing border cells demarcate hindgut subdomains. From stage 14 to stage 16 (C, dorsal view) the hindgut expands in diameter and length. (D–F) <i>tnc^13c</i> mutant embryos stained for Crb revealed a normal hindgut lumen at stage 13 (D), slight reduction in lumen diameter at stage 14 (E) and a clear reduction in lumen diameter at stage 16 (F), compared to the wild type. White and open arrowheads in (C′) and (F) illustrate lumen diameter of Li and Si, respectively. (G) Drawings of the hindgut lumen at stages 14 and 16 with Si in red and Li in blue. Border cells (black lines) mark anterior and posterior boundaries of Li and separates dorsal Li (dLi) and ventral Li (vLi). (H) The graphs show mean lumen diameter of Si and Li at stages 14 and 16 in the wild type and at stage 16 in <i>tnc^13c</i> mutants. Li expands in diameter from 6.3 (+/−0.09) µm to 8.8 (+/−0.16) µm, and Si from 8.9 (+/−0.52) µm to 17.3 (+/−0.56) µm. * = P-value<0.05. Bars represent standard error of mean (n>5). Scale bar: 10 µm. See also <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1002850#pgen.1002850.s002" target="_blank">Figures S2</a>, <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1002850#pgen.1002850.s003" target="_blank">S3</a>, <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1002850#pgen.1002850.s004" target="_blank">S4</a>.