Fig. 6. DIC sections taken from focus sweeps through a living Corella inflata embryo at three successive stages. (A-C) Sections through the neural plate/tube. (D-F) Sections through the dorsal notochord plate/cylinder/rod. (G-I) Sections through the dorsal notochord plate/cylinder/rod. (J-L) Sections through the endodermal strand. First column (A,D,G,J) just after completion of the final notochord cell division. Second column (B,E,H,K) mid-neurula stage, approximately 2 hours after the completion of the final division. Third column (C,F,I,L) stack of coins stage, approximately 6 hours after completion of the final division. By this stage, approximately half of the notochord has extended posterior beyond the field of view. Anterior is to the left in all panels. Asterisks in A,D,G mark the blastopore. Arrows in G and H indicate the boundaries of the notochord. Scale bar, 10 µm.