Urogenital folds.html



The urogenital folds (or urogenital ridges, or urethral folds) are an embryological structure which give rise to a portion of the external genitalia.

Differentiation

It differentiates into two structures: ^[1]

• gonadal ridge -- medial -- primarily reproductive system
• nephrogenic cord -- lateral -- primarily urinary system

Derivatives

• In the female, the urogenital folds become the labia minora. In contrast, the labia majora are formed by the labioscrotal folds ^[2]
• In the male, they form the spongy urethra and a portion of the shaft of the penis, not including the glans.

Pathology

In the male, failure of the urogenital folds to fuse during development leads to a condition known as hypospadias.

Obsolete meanings

Section of the fold in the mesonephros of a chick embryo of the fourth day. This can also be called urogenital fold, but shouldn't be confused with the main meaning.

Less commonly, urogenital fold refers to the fold in the mesonephros which is the precursor of e.g. the suspensory ligament of the ovary^[3]. This is the case in older versions of Gray's anatomy. See development of the urinary and reproductive organs, particularly the "The Mesonephros, Müllerian Duct, and Genital Gland" section for this meaning.

See also

• Fetal genitalia

External links

• "Development of Male External Genitalia", at mcgill.ca
• "Development of Female External Genitalia", at mcgill.ca
• Urogenital+folds at eMedicine Dictionary

References

1. ^ Netter, Frank H.; Cochard, Larry R. (2002). Netter's Atlas of human embryology. Teterboro, N.J: Icon Learning Systems, 158. ISBN 0-914168-99-1. 
2. ^ HSC - Gonad Descent and Development of External Genitalia II
3. ^ The University of North Texas Health Science Center - Genital System, page 44

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