Fig. 2. Presence of HA depends on Has2 activity and cannot be restored by constitutively active Rac1, whereas Fibronectin is unaffected in has2 morphants. (A-C) HA staining on transverse sections through the posterior region of 10-somite stage embryos. (A) Wild type; (B) embryo injected with has2 MO; (C) embryo co-injected with has2 MO and mRNA encoding constitutively active Rac1 (caRac1). At tailbud stage, the embryo in B was elongated, indicating convergence defects, the embryo in C was round like the wild-type control, indicating that convergence was rescued (compare with Fig. 4). Notochord and somites are outlined in B,C. (D,E) Anti-Fibronectin immunostaining. Section through posterior region of 3-somite stage embryos. (D) Wild type; (E) embryo injected with has2 MO. nc, notochord; nt, neural tube; s, somite.