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a furrow in the posterior region of the embryonic (primordial) disk. It indicates the cephalocaudal axis that results from the active involution of cells forming the primitive streak.
prim·i·tive groove(prim'i-tiv grūv)
The median depression in the primitive streak flanked by primitive ridges.
In the embryo, a shallow longitudinal midline groove in primitive streak of the blastoderm. The rostralmost end of the primitive groove becomes the primitive pit, a circular depression through which surface cells descend during gastrulation.
See also: groove
first in point of time; existing in a simple or early form; showing little evolution.
longitudinal furrow in the primitive streak of the embryo.
see hensen's node.
enlarged cranial end of the primitive streak.
the thickened median area of the epiblast which sets out the future longitudinal axis of the early embryo.