part of part of located in located in develops in develops in contributes to morphology of primitive knot primitive pit EHDAA2:0001521 The small depression in the primitive streak that is caudal to the primitive node where the cells of the epiblast initially begin to invaginate during early embryogenesis. UBERON:0004055 FMA:293120 NCIT:C34267 Wikipedia:Primitive_pit EHDAA:551 primitive streak notochordal process pit