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prim·i·tive groove(prim'i-tiv grūv)
The median depression in the primitive streak flanked by primitive ridges.
Medical Dictionary for the Health Professions and Nursing © Farlex 2012
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
Medical Dictionary, © 2009 Farlex and Partners