Voiculescu O, Bertocchini F, Wolpert L, Keller RE, Stern CD. The amniote primitive streak is defined by epithelial cell intercalation before gastrulation. Nature advance online publication 10 October 2007 | doi:10.1038/nature06211
This paper uses electroporation of Morpholino oligos into chick embryos to knock down genes involved in formation of the primitive streak. See the supplementary online information for videos.