The mesonephric duct (also known as the Wolffian duct, archinephric duct, Leydig's duct or nephric duct) is a paired

organ Organ may refer to: Biology * Organ (biology), a part of an organism Musical instruments * Organ (music), a family of keyboard musical instruments characterized by sustained tone ** Electronic organ, an electronic keyboard instrument ** Hammond ...

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.

Structure

The mesonephric duct connects the primitive kidney, the '' mesonephros'', 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 for male urogenital 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, and seminal vesicles.

Development

In both male and female the mesonephric duct develops into the trigone of urinary bladder, a part of the bladder wall, but the sexes differentiate in other ways during development of the urinary 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, it develops into a system of connected organs between the efferent ducts of the testis and the prostate, namely the

, the vas deferens, and the seminal vesicle. The prostate forms from the urogenital sinus and the efferent ducts form from the mesonephric tubules. For this it is critical that the ducts are exposed to testosterone 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 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 fluid.

Female

In the female, with the absence of anti-Müllerian hormone secretion by the Sertoli cells 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 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 or cyst could develop as a remnant.

Function

Sexual differentiation

History

It is named after Caspar Friedrich Wolff who described the mesonephros 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