Figure 4.

Lepisosteus osseus. Stages 11-15. A) Stage 11, lateral view. B) Stage 11, dorsal view. C) Stage 12, lateral view. D) Stage 13, dorsal view. E) Stage 14, lateral view. F) Stage 15, dorsal view. dl = dorsal lip ysl = yolk syncytial layer es = embryonic shield ez = evacuation zone at the animal pole gr = germ ring ng = neural groove ypl = yolk plug nf = neural fold bp = blastopore