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Fig. 2. Ectodermal expression of Xenopus Pitx genes at neurula stages. (A–C) Early neurula (stage 13), (D–F) mid-neurula (stage 18), (G–I) late neurula (stage 22). Lines indicate approximate levels of sections. (A*) and (C*–E*) show larger magnifications of sections. Note that Pitx1 and Pitx2c were co-expressed in the primordia of the cement gland (black arrow; A,C,D,F,G,I) and the stomodeum/pituitary (yellow arrow; (A–I)), while Pitx2b was resticted to the deep layer cells fated to become pituitary (B,E,H). Note also that Pitx1 was not expressed in the neuroectoderm, whereas Pitx2b and Pitx2c RNAs were found in neural tissue (red arrows; (F,H,I)). |