Urachus
Vertical section of bladder, penis, and urethra. Urachus is seen at top
Urachus is #1
Gray's	subject #252 1213
MeSH	Urachus

The urachus is an embryological canal connecting the urinary bladder of the fetus with the allantois, a structure that contributes to the formation of the umbilical cord. The lumen (inside) of the urachus is normally obliterated during embryonic development, transforming the urachus into a solid cord, a functionless remnant. The urachus lies in the space of Retzius, between the transversalis fascia anteriorly and the peritoneum posteriorly.

Contents 1 Formation 2 Pathology 3 Additional images 4 External links

[edit] Formation

The vesico-urethral portion of the urogenital sinus absorbs the ends of the Wolffian ducts and the associated ends of the renal diverticula, and these give rise to the trigone of the bladder and part of the prostatic urethra. The remainder of the vesico-urethral portion forms the body of the bladder and part of the prostatic urethra; its apex is prolonged to the umbilicus as a narrow canal, which later is obliterated as the urachus goes on to definitively form the median umbilical ligament (urachus). Note: The two medial umbilical ligaments are the obliterated umbilical arteries.

[edit] Pathology

Failure for the lumen of the urachus to be filled in leaves a patent (open) urachus. The telltale sign is leakage of urine through the umbilicus. A patent urachus needs to be surgically removed. There are four anatomical cases

• Urachal cyst: there is no connection between the bladder and the umbilicus
• Urachal fistula: there is free communication between the bladder and umbilicus
• Urachal diverticulum: the pouch opens toward the bladder
• Urachal sinus: the pouch opens toward the umbilicus (Guray, Sogut, et al. Urachal Cyst. Eastern Journal of Medicine 5 (2) : 76-78, 2000)

[edit] Additional images

Inguinal fossae

[edit] External links

• Urachus at eMedicine Dictionary
• Swiss embryology (from UL, UB, and UF) turinary/patholurinary07
• Persistent urachus at moorabbinvet.com.au
• Repair at pennhealth.com

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This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained within it may be outdated.

v • d • e Prenatal development/mammalian embryogenesis - Development of the urinary and reproductive organs (GA 11.1204) Common Urinary/Reproductive system Cloacal membrane - Cloaca - Urethral groove - Urogenital sinus - Urachus - Urogenital folds Kidney development Nephrogenic cord - Nephrotome - Pronephros - Mesonephros (Mesonephric tubules) Ureteric bud - Metanephric blastema Fetal genital development Primarily internal Gonadal ridge - Sex cord (Cortical cords, Testis cords) Pronephric duct/Wolffian duct/mesonephric duct - Müllerian duct/paramesonephric ducts (Vaginal plate) Primarily external Genital tubercle - Phallus - Labioscrotal folds Gubernaculum - Processus vaginalis Homologues List of homologues of the human reproductive system urinary system navs: anat/physio/dev, noncongen/acid+base/congen/neoplasia, symptoms+signs/eponymous, proc reproductive system navs: anat female,male/physio/dev, noncongen/congen/neoplasia, symptoms+signs/eponymous, proc