11. Mesentoblasts are found in the blastopore area between the endoderm and ectoderm . 12. Robins said the cells in the early primitive ectoderm develop in two directions. 13. Ectoderm follows a default pathway to become neural tissue.14. They found that ectoderm was more potent than endoderm. 15. It is formed by ectoderm and endoderm coming into contact with each other. 16. BMP signals from the epidermis inhibit the formation of placodes in nearby ectoderm . 17. The ectoderm is the outermost layer of the embryo. 18. Each tracheal tube develops as an invagination of the ectoderm during embryonic development. 19. Unlike bilaterians, radiata only have two primordial cell layers, endoderm and ectoderm . 20. The shells develop from the ectoderm as an organic framework which is subsequently mineralised.
