(A–F) Merged Z views of CBs from mutant embryos stained with Arm (red), Dg (green), and How (blue) antibodies at different stages of embryogenesis (from stages 13–14 in A to stage 16 in F)

A′–F′ show Arm and How, whereas A″–F″ show Dg and How staining. CBs keep their initial rounded shape during all stages of cardiac tube formation. Initially, Arm is correctly localized at the future J domains (arrowheads), but is not completely excluded from the Dg-positive domain as it is in the wild type (A′–C′, compared with ). When CBs join dorsally, Arm shows an extended area of expression compared with the wild type (Fig. 5, E and E′ [arrowheads], compare with ). Finally, in a few cases a lumen can be detected, Arm is localized all along the extended dorsal J domain (Fig. 5 F, compare arrowheads with ). (G) Schematic representation of CB shape dynamics and membrane domains in mutant embryos (compare with ). Step 1 is similar to that of the wild type except that the Arm-positive domain is larger in the mutant, and, as a consequence, Dg and Arm partially colocalize. (2) In the mutant, CBs do not change their shape, do not form a leading edge (3), and make contact by an enlarged Arm-positive J domain. Finally, CBs are either not able to form a lumen (4) or, rarely (5), they show an ectopic small lumen formed ventrally. Bars, 4 μm.<p><b>Copyright information:</b></p><p>Taken from "Genetic control of cell morphogenesis during cardiac tube formation"</p><p></p><p>The Journal of Cell Biology 2008;182(2):249-261.</p><p>Published online 28 Jul 2008</p><p>PMCID:PMC2483531.</p><p>