The genital ridge initially consists mainly of mesenchyme and cells of underlying mesonephric origin.
Once oogonia [clarification needed] enter this area they attempt to associate with these somatic cells.
The genital ridge appears at approximately five weeks, and gives rise to the sex cords.
[1] In the mouse gonadal primordium, the genital ridge, which forms from intermediate mesoderm, becomes morphologically distinct at E10.5.
Before E10.5, Dmrt1 is expressed at similar levels in the genital ridges of XX as well as XY embryos.
In mice, the genital ridge houses the transcript for SRY, the Y-chromosomal gene responsible for sex determination in mammals.