Primitive streak is initiated and maintained by: (A) Nodal gene, (B) BMP4, (C) FGF, (D) Brachyury gene
Answer is A. Ans. is 'a' i.e. Nodal gene "The primitive streak in itself is initiated and maintained by expression of Nodal, a member of the transforming growth factor b (TGFb) family." - Longman's Medical embryology 10/e, p 57