Inhibition of Rho/Rock activities enhances neural crest (NC) delamination from explanted neural primordia. (A,D,G) Phase contrast. (B,E,H) HNK-1. (C,F,I) Phalloidin staining of F-actin. In control explants (A,B), NC delamination is progressive, transiting through an epithelioid stage on the way to a mesenchymal phenotype. (B,E,H) Delaminating cells are HNK-1+ under all experimental conditions. (C,F,I) Control delaminating cells have F-actin+ stress fibers (arrows in (C)), whereas C3- and Y27632-treated explants show cortical actin but lack stress fibers. Instead, they adopt irregular morphologies with long protrusions (arrowheads in (F,I)). (J) Both C3 transferase and Y27632 stimulate NC delamination when compared to control (Ctr) (**p < 0.001) and promote the direct production of mesenchymal cells without epithelioid intermediates (D,E,G,H), but have no significant effect on cell proliferation (K). Bar: 100 μM, (A,D,G); 36 μM (B,E,H); 8 μM, C,F,I. BrdU, bromo-deoxyuridine; M, mesenchymal; NT, neural tube; SD, standard deviation.