Fig. 3. Ci-ephrin-Ad is broadly expressed in the animal hemisphere. (A) Ciona embryos at progressively older stages hybridized for Ci-ephrin-Ad. (B) Schematic representation of Ci-ephrin-Ad-expressing cells in the animal hemisphere. The black dots indicate blastomeres that express the gene. The Ci-ephrin-Ad transcript is present in all animal blastomeres at the 16-cell stage, but diminishes in two of the progenies, b6.5 and b6.7, at the 32-cell stage. Zygotic expression further diminishes at the 64-cell stage. The relative positioning of the b6.5 and A6.3 blastomeres is shown in the vegetal view of the 32-cell embryo.