Sex cords are embryonic structures which eventually will give rise (differentiate) to the adult gonads (reproductive organs).
[2] These epithelial cells (from the genital ridges) penetrate and invade the underlying mesenchyme to form the primitive sex cords.
[3] This occurs shortly before and during the arrival of the primordial germ cells (PGCs) to the paired genital ridges.
[8] These hormones drive the formation of the other male sex characteristics, and induce testicular descent out of the abdomen.
[2] After inducing female sex cord formation, coordination between multiple genes (Bmp, Pax2, Lim1, and Wnt4 in mice) is required for Müllerian duct development.
[12][2] The Hox genes are expressed in specific combinations to give rise to the fallopian tubes, uterus, and upper region of the vagina.
[13] In phase three, Müllerian ducts proliferate and elongate, subsequently forming the uterus and upper region of the vagina.