Both sexes have initially two pairs of genital ducts: the mesonephric (Wolffian) ducts and the paramesonephric (Müllerian) ducts.
The paramesonephric (Müllerian) duct arises as a longitudinal invagination of the coelomic epithelium on the anterolateral surface of the the urogenital ridge and empties into the urogenital sinus. It can be divided into three parts: a) the cranial part which opens into coelomic cavity, b) the horizontal part which crosses the mesonephric duct, and c) the caudal part which fuses with the same duct from the other side. The cranial parts develop into the uterine tubes while the caudal fused parts into the uterus, cervix and one third of the vagina. The surrounding layer of the mesenchyme forms the myometrium and perimetrium.

1. Abdominal ostium of uterine tube
2. Paramesonephric tubercule
3. Uterine canal
4. Paramesonephric duct
5. Cortical cords of ovary
6. Mesonephric duct
7. Mesonephros

When the paramesonephric ducts reach the urogenital sinus, two evaginations (sinovaginal bulbs) proliferate and form a solid vaginal plate. By the 5th month, this plate is completely canalized.
Thus, the vagina has a dual origin: upper one third derives from the paramesonephric duct and the lower two thirds from the urogenital sinus.

1. Symphysis
2. Uterine canal
3. Urinary bladder
4. Sinovaginal bulbs
5. Genital tubercle
6. Perineum
7. Anus

1. Urethra
2. Urinary bladder
3. Uterus
4. Fornix
5. Vagina
6. Hymen

The paramesonephric duct in the male degenerates, except for a small portion known as the appendix testis and utriculus prostaticus.
The mesonephric (Wolffian) duct arises by the canalization of a solid mass of cells in the urogenital ridge and empties into the urogenital sinus laterally to the paramesonephric duct orificies. It gives rise to the ductus epididymis, seminal vesicle, ductus deferens and ejaculatory duct. The mesonephric duct in female regresses, but may persist as the appendix vesiculosa, epoophoron or paroophoron and Gartner's duct. In both sexes, a branch of mesonephric duct forms the ureteric bud.

1. Mesonephric tubules
2. Rete testis
3. Mesonephric duct
4. Paramesonephric tubercule
5. Paragenital tubules
6. Testis cords
7. Tunica albuginea