Fig. 8. Xdd1 disrupts convergent extension of dorsolateral neural tissue. (A) Dorsal view Xpax3 expression (blue staining) in a control embryo at mid-neurula stage. (B) Xpax3 expression at mid-neurulation in an embryo injected with Xdd1. It should be noted that embryological and fate-mapping experiments have identified an additional convergent extension event which shapes the dorsal neural tube following overt tube closure (Davidson and Keller, 1999). This later convergent extension event was also disrupted by expression of Xdd1 (not shown). (C) Expression of Xash3 in a control embryo. (D) Expression of Xash3 in an Xdd1-injected embryo; the expression domains are foreshortened. (E) Expression of Sox2 in a control embryo at stage 14. (F) Expression pattern of Sox2 in Xdd1-injected embryos. As a control, we targeted Xdd1 injections to the dorsal, vegetal blastomeres, where expression inhibits predominantly mesodermal convergent extension and does not inhibit NT closure (Wallingford and Harland, 2001); in those embryos, Sox2 expression resembled wild type (not shown).