21. The top layer is now called the ectoderm . 22. The endoderm of the archenteron will fuse with the ectoderm of the blastocoel wall. 23. The embryo is covered on the dorsal surface by a layer of cells called ectoderm . 24. BMP4 antagonizes organizer tissue and is expressed in early development in ectoderm and mesoderm tissue. 25. Neural development happens in the dorsal ectoderm . 26. This represents the point of transition between the hindgut and the ectoderm in the embryo. 27. In triploblastic organisms, the three germ layers are called endoderm, ectoderm , and mesoderm. 28. The dorsal neural tube is patterned by BMPs from the epidermal ectoderm flanking the neural plate. 29. As the ectoderm proliferates, the notochord is dragged into the middle of the developing embryo. 30. By the 10 mm stage, the lens vesicle has completely separated from the surface ectoderm .
