Mesonephric duct

Mesonephric duct
Mesonephric duct
	Urogenital sinus of female human embryo of eight and a half to nine weeks old
Details
Carnegie stage	11
Days	28
Precursor	Intermediate mesoderm
Gives rise to	Vasa deferentia, seminal vesicles, epididymides, Gartner's duct
Identifiers
Latin	ductus mesonephricus; ductus Wolffi
MeSH	D014928
TE	duct_by_E5.6.2.0.0.0.4 E5.6.2.0.0.0.4
	Anatomical terminology [edit on Wikidata]

The mesonephric duct, also known as the Wolffian duct, archinephric duct, Leydig's duct or nephric duct, is a paired organ that develops in the early stages of embryonic development in humans and other mammals. It is an important structure that plays a critical role in the formation of male reproductive organs. The duct is named after Caspar Friedrich Wolff, a German physiologist and embryologist who first described it in 1759.^[1]

During embryonic development, the mesonephric ducts form as a part of the urogenital system.^[2]

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 epididymides, vasa deferentia, and seminal vesicles.

Development

In both males and females, the mesonephric ducts develop 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 organs.

Male

In a male, they develop 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. Testosterone binds to and activates androgen receptor, affecting intracellular signals and modifying the expression of numerous genes.^[3]

In the mature male, the function of this system is to store and mature sperm, 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, the mesonephric ducts regress, although inclusions may persist. The vestigial epoophoron arises from these ducts. Also, lateral to the wall of the vagina, a Gartner's duct 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.^[1]

Additional images

Diagrams to illustrate the changes in the cloaca in mammals during development. A, early embryonic stage, showing the cloaca receiving the urinary bladder, the rectum, and the Wolffian duct, as in the lower vertebrates. B, later stage, showing the beginning of the fold which divides the cloaca into a ventral urogenital sinus which receives the urinary bladder, Wolffian ducts, and ureters, and into a dorsal part which receives the rectum. C, further progress of the fold, dividing the cloaca into urogenital sinus and rectum; the ureter has separated from the Wolffian duct and is shifting anteriorly. D, completion of the fold, showing complete separation of the cloaca into ventral urogenital sinus and dorsal rectum.

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

References

^ ^a ^b synd/2845 at Who Named It?
^ Du, Hongling; Taylor, Hugh S. (January 1, 2015). "Chapter 27 - Development of the Genital System". In Moody, Sally A. (ed.). Principles of Developmental Genetics (Second ed.). Academic Press. pp. 487–504. doi:10.1016/b978-0-12-405945-0.00027-2. ISBN 9780124059450 – via ScienceDirect.
^ Hannema SE, Print CG, Charnock-Jones DS, Coleman N, Hughes IA (2006). "Changes in gene expression during Wolffian duct development". Horm. Res. 65 (4): 200–9. doi:10.1159/000092408. PMID 16567946. S2CID 2444520.

External links

How the Body Works / Sex Development / Sexual Differentiation / Duct Differentiation - The Hospital for Sick Children (GTA - Toronto, Ontario, Canada)

[auto-1] synd/2845 at Who Named It?

[2] Du, Hongling; Taylor, Hugh S. (January 1, 2015). "Chapter 27 - Development of the Genital System". In Moody, Sally A. (ed.). Principles of Developmental Genetics (Second ed.). Academic Press. pp. 487–504. doi:10.1016/b978-0-12-405945-0.00027-2. ISBN 9780124059450 – via ScienceDirect.

[pmid16567946-3] Hannema SE, Print CG, Charnock-Jones DS, Coleman N, Hughes IA (2006). "Changes in gene expression during Wolffian duct development". Horm. Res. 65 (4): 200–9. doi:10.1159/000092408. PMID 16567946. S2CID 2444520.

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