primitive ridge

prim·i·tive ridge

one of the paired ridges on either side of the primitive groove.

primitive ridge

a ridge that bounds the primitive groove in the early stages of embryonic development. Also called primitive fold. See also primitive streak.
References in periodicals archive ?
We lived close to 3rd Baptist Church in a small village called Primitive Ridge, about a mile from West Blocton and Blocton (Alabama).
I went to school in Primitive Ridge past the 7th grade, then I went to J.