Development of the reproductive system

The development of the reproductive system is the part of embryonic growth that results in the sex organs and contributes to sexual differentiation. Due to its large overlap with development of the urinary system, the two systems are typically described together as the genitourinary system.

The reproductive organs develop from the intermediate mesoderm and are preceded by more primitive structures that are superseded before birth. These embryonic structures are the mesonephric ducts (also known as Wolffian ducts) and the paramesonephric ducts, (also known as Müllerian ducts). The mesonephric duct gives rise to the male seminal vesicles, epididymides and vasa deferentia. The paramesonephric duct gives rise to the female fallopian tubes, uterus, cervix, and upper part of the vagina.

The mesonephric duct originates from a part of the pronephric duct.

In the outer part of the intermediate mesoderm, immediately under the ectoderm, in the region from the fifth cervical segment to the third thoracic segment, a series of short evaginations from each segment grows dorsally and extends caudally, fusing successively from before backward to form the pronephric duct. This continues to grow caudally until it opens into the ventral part of the cloaca; beyond the pronephros it is termed the mesonephric duct. Thus, the mesonephric duct remains after the atrophy of the pronephros duct.

In the male, the duct persists, and forms the tube of the epididymis, the vas deferens and the ejaculatory duct, while the seminal vesicle arises during the third month as a lateral diverticulum from its hinder end. A large part of the head end of the mesonephros atrophies and disappears; of the remainder the anterior tubules form the efferent ducts of the testicle; while the posterior tubules are represented by the ductuli aberrantes, and by the paradidymis, which is sometimes found in front of the spermatic cord above the head of the epididymis.

In the female, the mesonephric bodies and ducts atrophy. The nonfunctional remains of the mesonephric tubules are represented by the epoophoron, and the paroöphoron, two small collections of rudimentary blind tubules which are situated in the mesosalpinx.

The lower part of the mesonephric duct disappears, while the upper part persists as the longitudinal duct of the epoöphoron, called Gartner's duct.

There are also developments of other tissues from the mesonephric duct that persist, e.g. the development of the suspensory ligament of the ovary.