[1] Primitive streak:During the development usually on day 15, a thickened linear band of epiblast known as the primitive streak appears caudal in the midline of the dorsal aspect of the embryonic disc.
It is clearly visible as a narrow groove with slightly bulging regions on either side.
KEITH. L. Moore. The Developing Human, page 54.
Human embryology 4th edition, page 69.
[2] Teratoma :- Containing Representative cells from all three embryonic Layers ( ectoderm, Mesoderm, endoderm) and containing hair, teeth, muscle, glands,…
The precise origin of teratoma probably from migrating totipotential cells found in proximity to the hensens node in the early embryo the peak incidence is in the second and third decades.
1- Sho practice of surgery page102
2- Sabiston text book of surgery 16th edition page
[3] .Human embryology, 4th edition page 196