21. Research can only be performed on an embryo for a maximum of fourteen days or until the primitive streak appears. 22. Amphioxus forms an epithelial neural tube and dorsal notochord but does not have the EMT potential of the primitive streak . 23. The neural plate will form opposite the primitive streak from ectodermal tissue which thickens and flattens into the neural plate. 24. Transplantation of the PMZ results in induction of a primitive streak , however, PMZ does not contribute to the streak itself. 25. The lateral plate and the extraembryonic mesoderm arise from the cells that enter at the posterior end of the primitive streak . 26. The Foundation has collaborated with many scientists, notably Primitive Streak , Mental, Wonderland, Eye & I and Dress of Glass and Flame. 27. A primitive node ( or primitive knot ) forms in front of the primitive streak which is the organiser of neurulation. 28. The first wave of epiblast cells to invaginate through the primitive streak invades and displaces the hypoblast to become the embryonic endoderm. 29. Otx2 is a group of homeobox genes that are typically described as a head organizer in the primitive streak stage of embryonic development. 30. In the first 14 days of life, the embryo has not yet developed a " primitive streak , " the precursor to a backbone.
