Apical-basal components display asymmetric distribution.

<p>(A) Stage 15 epithelium with junctions in green (Arm) and denticle precursors in red (pTyr). Note the rectangular cell shapes of denticle-secreting cells, versus the squamous, irregular shape of cells that do not secrete denticles. Notice also the asymmetric Arm distribution, and actin-based denticle precursors localized to the posterior of cells. (B) A stage 15 ventral epithelium showing polarity protein aPKC enriched at the D/V margins of cells. (C) Schema of a stage 15 embryonic ventral epithelium. The apical components and adherens junction components are asymmetrically distributed to the D/V margins of cells. The baso-lateral components are asymmetrically distributed to the A/P margins of cells. Rectangular cells produce an actin-based precursor at the posterior edge of cells. (D-E) Cuticle of wild-type denticles, with denticle rows properly aligned. (F) Denticle belt of an <i>aPKC</i> mutant, which has very slightly misaligned denticle rows. (G) An embryo overexpressing aPKC also shows little to no phenotype, with very mild denticle misalignment. (H) Ventral epithelium of an <i>aPKC</i> mutant showing that the aPKC protein is still present at cell membranes in the mutant embryo. Anterior to posterior (A/P) and dorsal to ventral (D/V) directions are shown in the schematic (C) and this orientation is maintained in all figures. Scale bar = 20 µm.