part of part of contributes to morphology of embryonic structure primitive groove The shallow valley that extends along the length of the primitive streak[MP]. Wikipedia:Primitive_groove UBERON:0004056 UMLS:C1514434 A shallow groove, the primitive groove, appears on the surface of the primitive streak, and the anterior end of this groove communicates by means of an aperture, the blastophore, with the yolk-sac[Wikipedia:Primitive_groove]. NCIT:C34265 FMA:293118 EHDAA2:0001511 EHDAA:547 primitive streak