Fig. 5. Myosin localization in Rho-kinase mutant embryos. Staining for Dorsal protein (red) marks ventral cells, nuclei are Hoechst stained (blue) and anti-myosin II antibody staining is in green. (A-F) Myosin localization in control embryos (A-C) and equivalently staged Rho-kinase (ROK) mutant embryos (below, D-F). ROK embryos have irregular incorporation of myosin to the cellularization front (+, myosin present; –, reduced myosin incorporation), irregular nuclear morphology and a failure to localize myosin to the apical side of ventral cells at the onset of gastrulation (compare asterisk in C,F). (G-K) Control embryos (G,H) and ROK mutant embryos (J,K) at later stages of development. Cells in later ROK mutant embryos are irregular (K). e, epidermal cell layer; f, folds; m, mesodermal cell layer. (I,L) nullo mutant embryos show both basal loss (arrow) and apical localization of myosin (asterisk) in ventral cells at gastrulation (L), despite earlier cellularization defects (I).