True about primitive streak are all except ?

Appear at cranial endGastrulation is the morphogenic process of formation of three germ layers, i.e. ectoderm, mesoderm and endoderm.The embryo at this stage is called gastrula.The process of gastrulation begins with formation of primitive streak.Primitive streak is formed by proliferation of some of epiblast cells near the caudal end of bilaminar germ disc (embryonic disc).The epiblast throuth the process of gastrulation, is the source of all three germ layers in embryo :-Some cells of epiblast after invagination displace the hypoblast and form embryonic endoderm. Endoderm is the first germ layer to be formed.Some epiblast cells after invagination come to lie between the epiblast and hypoblast, and form mesoderm.Cells remaining in the epiblast than form ectoderm.