Fig. 14. Uncoupling of blastopore closure and archenteron elongation. (A,a') Embryos fixed at mid (A) and late (a') gastrula stages are plotted to show the combined progress in both convergent extension and blastopore closure. (B,b') Embryos fixed at mid (B) and late (b') gastrula stages are plotted to show the combined progress in both blastopore closure and archenteron elongation. Xdd1-injected embryos make essentially no progress in convergent extension between the two time points, but progress significantly in both blastopore closure and archenteron elongation.