Fig. 8. Canonical Wg and Hh signaling are required for denticle polarity. Embryos, anterior left. F-actin (green or single label; phalloidin, A-H,L-M; anti-actin, J,K,N-P). Cell outlines (red; P-Tyr, E-H,M; anti-Arm, J,K,N-P). B-H. Actin condensation and denticle formation are not restricted to the posterior margin. Some denticles form at the cell apex (red arrowheads), while others form at anterior or posterior cell junctions (yellow and white arrowheads, respectively). A-C,E,F, wg^IG22. D, wg; Df(3L)H99. (A) All cells remain cuboidal and accumulate apical actin (beginning laterally; brackets). (B,C) Actin condensations form (B) and sharpen (C). (D) Denticle polarity is lost even if cell death is blocked. (E) Denticle elongation. (F) Elongated denticles. (G,H) Embryos maternally and zygotically dsh⁷⁵ (G) or arm^XM19 (H). (I) Stills, movie of wg^IG22 embryo expressing Moesin-GFP. Time in hours: minutes. Colored arrows – condensations. (J-L) arm^XP33 zygotic mutants. Many cells retain normal polarity (white arrows). A subset have reversed polarity (yellow arrows) or lose polarity (blue arrows). (K) Closeup, bracketed area in J. (L) Polarity reversals remain in elongated denticles. (M) UAS-Fz2-GPI expressed using Rho-GAL4. Occasional polarity reversals (red arrows). (N,O) hh^AC. (N) Condensation polarity is lost (white arrow). Many cells produce multiple denticles (blue arrows). (O) Denticles elongating; no segmental periodicity. (P) ptc⁹. Many cells form apical condensations (arrows). Scale bars, 5 µm.