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 An embryo is an initial stage of development of a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male sperm ...

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 system, 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 mesone ...

'', to the

cloaca In animal anatomy, a cloaca ( ), plural cloacae ( or ), is the posterior orifice that serves as the only opening for the digestive, reproductive, and urinary tracts (if present) of many vertebrate animals. All amphibians, reptiles and birds, a ...

. It also serves as the

primordium A primordium (; plural: primordia; synonym: anlage) in embryology, is an organ or tissue in its earliest recognizable stage of development. Cells of the primordium are called primordial cells. A primordium is the simplest set of cells capable o ...

for male

urogenital The genitourinary system, or urogenital system, are the organs of the reproductive system and the urinary system. These are grouped together because of their proximity to each other, their common embryological origin and the use of common pathwa ...

structures including the

epididymis The epididymis (; plural: epididymides or ) is a tube that connects a testicle to a vas deferens in the male reproductive system. It is a single, narrow, tightly-coiled tube in adult humans, in length. It serves as an interconnection between the ...

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, con ...

and

reproductive The reproductive system of an organism, also known as the genital system, is the biological system made up of all the anatomical organs involved in sexual reproduction. Many non-living substances such as fluids, hormones, and pheromones are als ...

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 The efferent ducts (or efferent ductules or ductuli efferentes or ductus efferentes or vasa efferentia) connect the rete testis with the initial section of the epididymis.Hess 2018 There are two basic designs for efferent ductule structure: * ...

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

, the

, and the

. The

prostate The prostate is both an Male accessory gland, 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, ...

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 we ...

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 conne ...

. 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 system, male reproductive tissues such as testes and prostate, as well as promoting secondar ...

during

embryogenesis An embryo is an initial stage of development of a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male sperm ...

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 system, male reproductive tissues such as testes and prostate, as well as promoting secondar ...

binds to and activates

androgen receptor The androgen receptor (AR), also known as NR3C4 (nuclear receptor subfamily 3, group C, member 4), is a type of nuclear receptor that is activated by binding any of the androgenic hormones, including testosterone and dihydrotestosterone in th ...

, 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 Sperm is the male reproductive cell, or gamete, in anisogamous forms of sexual reproduction (forms in which there is a larger, female reproductive cell and a smaller, male one). Animals produce motile sperm with a tail known as a flagellum, whi ...

, 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. Semen i ...

fluid.

Female

In the

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

, 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 Apoptosis (from grc, ἀπόπτωσις, apóptōsis, 'falling off') is a form of programmed cell death that occurs in multicellular organisms. Biochemical events lead to characteristic cell changes (morphology) and death. These changes incl ...

, the mesonephric duct regresses, although inclusions may persist. The

epoophoron The epoophoron or epoöphoron (also called organ of RosenmüllerJ. C. Rosenmüller. De ovariis embryonum et foetuum humanorum. 1802. or the parovarium) is a remnant of the mesonephric tubules that can be found next to the ovary and fallopian tu ...

and

Skene's glands In female human anatomy, Skene's glands or the Skene glands ( , also known as the lesser vestibular glands, paraurethral glands) are glands located around the lower end of the urethra. The glands are surrounded by tissue that swells with blood d ...

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 Caspar Friedrich Wolff (18 January 1733 – 22 February 1794) was a German physiologist and one of the founders of embryology. Life Wolff was born in Berlin, Brandenburg. In 1759 he graduated as an M.D. from the University of Halle with his diss ...

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