The mesonephric duct (also known as the Wolffian duct, archinephric duct, Leydig's duct or nephric duct) is a paired organ that forms during the embryonic development of humans and other mammals and gives rise to male

reproductive organs A sex organ (or reproductive organ) is any part of an animal or plant that is involved in sexual reproduction. The reproductive organs together constitute the reproductive system. In animals, the testis in the male, and the ovary in the female, a ...

Structure

The mesonephric duct connects the primitive kidney, the ''

mesonephros The mesonephros ( el, middle kidney) is one of three excretory organs that develop in vertebrates. It serves as the main excretory organ of aquatic vertebrates and as a temporary kidney in reptiles, birds, and mammals. The mesonephros is included ...

'', to the cloaca. It also serves as the primordium for male urogenital structures including the epididymis,

vas deferens The vas deferens or ductus deferens is part of the male reproductive system of many vertebrates. The ducts transport sperm from the epididymis to the ejaculatory ducts in anticipation of ejaculation. The vas deferens is a partially coiled tube ...

, and

seminal vesicle The seminal vesicles (also called vesicular glands, or seminal glands) are a pair of two convoluted tubular glands that lie behind the urinary bladder of some male mammals. They secrete fluid that partly composes the semen. The vesicles are 5� ...

Development

In both male and female the mesonephric duct develops into the

trigone of urinary bladder The trigone (a.k.a. vesical trigone) is a smooth triangular region of the internal urinary bladder formed by the two ureteric orifices and the internal urethral orifice. The area is very sensitive to expansion and once stretched to a certai ...

, a part of the bladder wall, but the sexes differentiate in other ways during development of the

urinary The urinary system, also known as the urinary tract or renal system, consists of the kidneys, ureters, bladder, and the urethra. The purpose of the urinary system is to eliminate waste from the body, regulate blood volume and blood pressure, co ...

and reproductive organs.

Male

In a

male Male (symbol: ♂) is the sex of an organism that produces the gamete (sex cell) known as sperm, which fuses with the larger female gamete, or ovum, in the process of fertilization. A male organism cannot reproduce sexually without access to ...

, it develops into a system of connected organs between the efferent ducts of the

testis A testicle or testis (plural testes) is the male reproductive gland or gonad in all bilaterians, including humans. It is homologous to the female ovary. The functions of the testes are to produce both sperm and androgens, primarily testostero ...

and the prostate, namely the epididymis, the

, and the

. The

prostate The prostate is both an accessory gland of the male reproductive system and a muscle-driven mechanical switch between urination and ejaculation. It is found only in some mammals. It differs between species anatomically, chemically, and phys ...

forms from the

urogenital sinus The urogenital sinus is a part of the human body only present in the development of the urinary and reproductive organs. It is the ventral part of the cloaca, formed after the cloaca separates from the anal canal during the fourth to seventh w ...

and the efferent ducts form from the

mesonephric tubules Mesonephric tubules are genital ridges that are next to the mesonephros. In males, some of the mesonephric kidney tubules, instead of being used to filter blood like the rest, "grow" over to the developing testes, penetrate them, and become conn ...

. For this it is critical that the ducts are exposed to

testosterone Testosterone is the primary sex hormone and anabolic steroid in males. In humans, testosterone plays a key role in the development of male reproductive tissues such as testes and prostate, as well as promoting secondary sexual characteristi ...

during embryogenesis.

Testosterone Testosterone is the primary sex hormone and anabolic steroid in males. In humans, testosterone plays a key role in the development of male reproductive tissues such as testes and prostate, as well as promoting secondary sexual characteristi ...

binds to and activates androgen receptor, affecting intracellular signals and modifying the expression of numerous genes. In the mature male, the function of this system is to store and mature sperm, and provide accessory

semen Semen, also known as seminal fluid, is an organic bodily fluid created to contain spermatozoa. It is secreted by the gonads (sexual glands) and other sexual organs of male or hermaphroditic animals and can fertilize the female ovum. Sem ...

fluid.

Female

In the

female Female ( symbol: ♀) is the sex of an organism that produces the large non-motile ova (egg cells), the type of gamete (sex cell) that fuses with the male gamete during sexual reproduction. A female has larger gametes than a male. Females ...

, with the absence of

anti-Müllerian hormone Anti-Müllerian hormone (AMH), also known as Müllerian-inhibiting hormone (MIH), is a glycoprotein hormone structurally related to inhibin and activin from the transforming growth factor beta superfamily, whose key roles are in growth differen ...

secretion by the

Sertoli cells Sertoli cells are a type of sustentacular "nurse" cell found in human testes which contribute to the process of spermatogenesis (the production of sperm) as a structural component of the seminiferous tubules. They are activated by follicle-stimula ...

and subsequent Müllerian apoptosis, the mesonephric duct regresses, although inclusions may persist. The epoophoron and Skene's glands may be present. Also, lateral to the wall of the vagina a

Gartner's duct Gartner's duct, also known as Gartner's canal or the ductus longitudinalis epoophori, is a potential embryological remnant in human female development of the mesonephric duct in the development of the urinary and reproductive organs. It was disco ...

or cyst could develop as a remnant.

Function

Sexual differentiation

History

It is named after Caspar Friedrich Wolff who described the

and its ducts in his dissertation in 1759.

Additional images

File:Gray29.png, Diagram of a transverse section, showing the mode of formation of the amnion in the chick. File:Gray986.png, Reconstruction of a human embryo of 17 mm. File:Gray992.png, Cloaca of human embryo from twenty-five to twenty-seven days old. File:Gray1116.png, Tail end of human embryo thirty-two to thirty-three days old. File:Gray1117.png, Tail end of human embryo; from eight and a half to nine weeks old.

References

External links

How the Body Works / Sex Development / Sexual Differentiation / Duct Differentiation
- The Hospital for Sick Children (GTA - Toronto, Ontario, Canada) {{Authority control Embryology of urogenital system