gonadal ridge
genital ridge
In embryology, the gonadal ridge (or genital ridge) is the precursor to the gonads and appears at approximately five weeks. . The gonadal ridge initially consists mainly of mesenchyme and cells of underlying mesonephric origin.
Once oogonia enter this area they attempt to associate with these somatic cells. Development proceeds and the oogonia become fully surrounded by a layer of cells (pre-granulosa cells). It gives rise to the sex cords.
See also
gonadal development
urogenital folds
sex cords