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 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. It also serves as the
primordium for male
urogenital structures including the
epididymis,
vas deferens, and
seminal vesicles.
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 certain ...
, a part of the bladder wall, but the sexes differentiate in other ways during development of the
urinary 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 and the prostate, namely the
epididymis, 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 spe ...
.
Testosterone 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
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, ...
, 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. Fema ...
, 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 in ...
, 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 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 dis ...
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.
See also
*
Fetal genital development
The development of the reproductive system is the part of prenatal development, 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 s ...
*
List of homologues of the human reproductive system
*
Masculinization
Virilization or masculinization is the biological development of adult male characteristics in young males or females. Most of the changes of virilization are produced by androgens.
Virilization is most commonly used in three medical and biology ...
*
Müllerian duct
*
Sexual differentiation
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