Urinary Bladder Development

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Adult urinary bladder
Adult male and female urinary bladder
Interior of the urinary bladder
Interior of the urinary bladder

The paired adult kidneys filter blood, reabsorb water, have endocrine functions and excrete waste. The waste in the form of urine for excretion, collects initially in the renal pelvis and flows through the ureters to the urinary bladder. The wall of the urinary bladder is composed of layers of smooth muscle and in the male has close anatomical relationship with the prostate gland. (More? Prostate Development)

Abnormalities in renal development can lead to ureter obstruction and interfere with flow of urine to the bladder during the fetal period.

The common name for the urinary bladder is simply the "bladder".

Renal Links: Introduction | Lecture - Renal | Lecture Movie | Urinary Bladder | Stage 13 | Stage 22 | Fetal | Renal Movies | Stage 22 Movie | Histology | Abnormalities | Molecular | Category:Renal
Historic Embryology - Renal  
1907 Urogenital images | 1911 Cloaca | 1921 Urogenital Development | 1915 Renal Artery | 1917 Urogenital System | 1925 Horseshoe Kidney | 1926 Embryo 22 Somites | 1930 Mesonephros 10 to 12 weeks | 1931 Horseshoe Kidney | 1932 Renal Absence | 1939 Ureteric Bud Agenesis | 1943 Renal Position

Historic Bladder: 1912 Cloaca, Bladder, Urethra, and Urogenital Sinus | 1921 Urinary Bladder

Some Recent Findings

Mouse cloacal septation
  • Morphology of the fetal bladder during the second trimester: Comparing genders[1] "Forty bladders, which were obtained from 40 human fetuses (20 males and 20 females) ranging in age from 13 to 23 weeks post-conception (WPC), were studied. The fetuses weighed between 60 and 490 g, and had crown-rump lengths between 9.5 and 20.4 cm. No elastic system fibers were observed in any bladders. ...The histological analysis of the smooth muscle, collagen, nerves and connective tissue of the developing bladders revealed that there are no gender differences during weeks 13-23 of gestation."
  • Spatio-temporal distribution of Smads and role of Smads/TGF-β/BMP-4 in the regulation of mouse bladder organogenesis[2]"Although Shh, TGF-β and BMP-4 regulate radial patterning of the bladder mesenchyme and smooth muscle differentiation, it is not known what transcription factors, local environmental cues or signaling cascades mediate bladder smooth muscle differentiation. ...Based on the Smad expression patterns, we suggest that individual or combinations of Smads may be necessary during mouse bladder organogenesis and may be critical mediators for bladder smooth muscle differentiation." TGF-beta
  • Endodermal origin of bladder trigone inferred from mesenchymal-epithelial interaction [3] "In the classic view of bladder development the trigone originates from the mesoderm derived wolffian ducts while the remainder of the bladder originates from the endoderm derived urogenital sinus. Recent molecular developmental studies have questioned the veracity of this received wisdom, suggesting an endodermal origin for the trigone. To shed further light on this issue we observed mesenchymal-epithelial interactions between trigone epithelium and fetal urogenital sinus mesenchyma to infer the trigonal germ layer of origin."
More recent papers  
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This table shows an automated computer PubMed search using the listed sub-heading term.

  • Therefore the list of references do not reflect any editorial selection of material based on content or relevance.
  • References appear in this list based upon the date of the actual page viewing.

References listed on the rest of the content page and the associated discussion page (listed under the publication year sub-headings) do include some editorial selection based upon both relevance and availability.

Links: References | Discussion Page | Pubmed Most Recent | Journal Searches

Search term: Bladder Embryology

Marta Pokrywczynska, Arkadiusz Jundzill, Karolina Warda, Lukasz Buchholz, Marta Rasmus, Jan Adamowicz, Magdalena Bodnar, Andrzej Marszalek, Anna Helmin-Basa, Jacek Michalkiewicz, Maciej Gagat, Alina Grzanka, Malgorzata Frontczak-Baniewicz, Agata Magdalena Gastecka, Tomasz Kloskowski, Maciej Nowacki, Camillo Ricordi, Tomasz Drewa Does the Mesenchymal Stem Cell Source Influence Smooth Muscle Regeneration in Tissue-Engineered Urinary Bladders? Cell Transplant: 2017, 26(11);1780-1791 PubMed 29338385

Mohammed Alae Touzani, Othmane Yddoussalah [IIA2-Y-type urethral duplication]. [Duplicité de l’urètre de type IIA2 en “Y”.] Pan Afr Med J: 2017, 27;254 PubMed 29187923

Fuman She, Shengwen Dong, Bibo Yuan, Xiaoli Gao Diagnosis of fetal megacystis with chromosomal abnormality by 2D prenatal ultrasound: A case report. Medicine (Baltimore): 2017, 96(46);e8589 PubMed 29145274

Amy Godfrey, Blair Hooser, Ahmed Abdelmoneim, Katharine A Horzmann, Jennifer L Freemanc, Maria S Sepúlveda Thyroid disrupting effects of halogenated and next generation chemicals on the swim bladder development of zebrafish. Aquat. Toxicol.: 2017, 193;228-235 PubMed 29101780

Vincenzo Petrozza, Antonio Luigi Pastore, Giovanni Palleschi, Claudia Tito, Natale Porta, Serena Ricci, Chiara Marigliano, Manuela Costantini, Giuseppe Simone, Angelina Di Carlo, Michele Gallucci, Antonio Carbone, Francesco Fazi Secreted miR-210-3p as non-invasive biomarker in clear cell renal cell carcinoma. Oncotarget: 2017, 8(41);69551-69558 PubMed 29050224

Textbook References

  • The Developing Human: Clinically Oriented Embryology (8th Edition) by Keith L. Moore and T.V.N Persaud - Moore & Persaud Chapter 13 p303-346
  • Larsen’s Human Embryology by GC. Schoenwolf, SB. Bleyl, PR. Brauer and PH. Francis-West - Chapter 10 p261-306


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 ‎‎Renal Overview
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 ‎‎Urogenital Septum
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 ‎‎GIT Stage 13
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 ‎‎Renal Vascular
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Renal System Development | All Renal Cartoons


File:Endoderm development Endoderm 002 icon.jpg

Animation - Endoderm forming the cloaca and the primitive urinary bladder continuous with the allantois.

  • hindgut region ending at the cloacal membrane
  • divided (ventro-dorsally) by the urogenital septum
    • ventral - common urogenital sinus
    • dorsal - rectum

Common Urogenital Sinus

  • superior end continuous with allantois
  • common urogenital sinus and mesonephric duct fuse (connect)
  • differentiates to form the bladder
  • inferior end forms urethra
    • this will be different in male and female development

Urogenital septum 001 icon.jpg

Urogenital Septum

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 ‎‎Urogenital Septum
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Embryonic Urinary Bladder

Adult bladder
  • early origins of the bladder at the superior end of the common urogenital sinus
  • 8 open inferiorly to the cloaca and superiorly to the allantois
  • Septation of the claoca - divides the anterior region to the primordial bladder component from the posterior rectal component.
  • associated ureters and urethra

Dorsal view of developing bladder

Trigone 001 icon.jpg
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  • Ultrasound measurement of the bladder size can be used as a diagnostic tool for developmental abnormalities.

Bladder Structure

Urinary bladder histology

Can be described anatomically by its 4 layers from outside inward:

  • Serous - the superior or abdominal surfaces and the lateral" surfaces of the bladder are covered by visceral peritoneum, the serous membrane (serosa) of the abdominal cavity, consisting of mesthelium and elastic fibrous connective tissue.
  • Muscular - the detrusor muscle is the muscle of the urinary bladder wall.
  • Submucosa - connects the muscular layer with the mucous layer.
  • Mucosa - (mucus layer) a transitional epithelium layer formed into folds (rugae).
Urinary bladder wall drawing

Detrusor Muscle

  • The adult detrusor muscle consists of three layers of smooth (involuntary) muscle fibres.
    • external layer - fibres arranged longitudinally
    • middle layer - fibres arranged circularly
    • internal layer - fibres arranged longitudinally

Ureter Development

  • The adult ureter is a thick-walled muscular tube, 25 - 30 cm in length, running from the kidney to the urinary bladder.
  • Anatomically can be described in two parts the abdominal part (pars abdominalis) and pelvic part (pars pelvina).
  • The ureter is composed of three layers: outer fibrous layer (tunica adventitia), muscular layer (tunica muscularis) and mucous layer (tunica mucosa).
  • The muscular layer can also be subdivided into 3 fibre layers: an external longitudinal, a middle circular, and an internal longitudinal.

Trigone Development

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Week 8

The Carnegie stage 22 human male embryo is 27mm (CRL) in size and approximately equal to day 54 - 56 of development. These images have been selected to show some key features of late embryo development.

Stage 22 image 196.jpg Stage 22 image 197.jpg Stage 22 image 198.jpg Stage 22 image 213.jpg Stage 22 image 214.jpg
G5 urogenital G6 urogenital G7 urogenital unlabeled labeled
Links: Stage 13 - Renal | Stage 22 - Renal | Carnegie stage 13 | Carnegie stage 22

Fetal Urinary Bladder

Fetal Development - 10 Weeks - Early female fetal bladder development. Anatomically lying behind the pubic symphysis and in front of the developing uterus. Surrounded by the developing detrusor muscle and the superior end extending towards the ventral body wall herniation.

Fetal 10wk urogenital 4.jpg Fetal 10wk urogenital 3.jpg
midline section medial section
Links: Fetal Development - 10 Weeks
Fetal kidney MRI 01.jpg MRI appearance of normal fetal kidney.[4] Sagittal T2- SSFSE of a fetal abdomen at GA 25 week. Adequate volume of the amniotic fluid and the developing lungs indicate good renal function.

  • two arrowheads - note the size and the signal appearance of the normal kidney.
  • white arrow - the fluid-filled urinary bladder
  • black arrow - the developing lung.

Note that the urinary bladder can occupy a considerable portion of the abdomen as a normal finding.

Links: Magnetic Resonance Imaging

Newborn Urinary Bladder

Gray1137.jpg Gray1138.jpg
The Newborn Male Bladder The Newborn Female Bladder

Animal Models

Mouse bladder development E12.5-E16.5.jpg Mouse bladder development E12.5-E16.5[2]


Australian abnormalities pie urogen.png

Duplicated Bladder

Neonatal duplicated bladder MRI Urinary bladder duplication is an extremely rare abnormality.[5]

This MRI of a male newborn infant shows the duplicated bladder and also duplicated external genitalia (phallus).

  • red arrow - collapsed right bladder
  • blue arrow - distended left bladder
  • orange arrow - midline septum
  • yellow arrow - right phallus
  • green arrow - left phallus

Links: Magnetic Resonance Imaging

Horseshoe Kidney

Horseshoe kidney
  • fusion of the lower poles of the kidney.
  • During migration from the sacral region the two metanephric blastemas can come into contact, mainly at the lower pole.
  • The ureters pass in front of the zone of fusion of the kidneys.
  • The kidneys and ureters usually function adequately but there is an increased incidence of upper urinary tract obstruction or infection.
  • Some horseshoe variations have been described as having associated ureter abnormalities including duplications.

Urorectal Septum Malformation

  • thought to be a deficiency in caudal mesoderm which in turn leads to the malformation of the urorectal septum and other structures in the pelvic region.
  • Recent research has also identified the potential presence of a persistent urachus prior to septation of the cloaca (common urogenital sinus).


  • absent or small bladder - associated with renal agenesis.

Bladder Exstrophy

  • developmental abnormality associated with bladder development.
  • origins appear to occur not just by abnormal bladder development, but by a congenital malformation of the ventral wall of abdomen (between umbilicus and pubic symphysis).
  • There may also be other anomolies associated with failure of closure of abdominal wall and bladder (epispadias, pubic bone anomolies).

Ureter and Urethra

  • Ureter - Duplex Ureter
  • Urethra- Urethral Obstruction and Hypospadias

Prune Belly Syndrome

  • lower urinary tract obstruction
  • mainly male
  • fetal urinary system ruptures leading to collapse and "prune belly" appearance.

Stage 22

Stage 22 image 210.jpg


Historic Images

Text-Book of Embryology. Bailey, F.R. and Miller, A.M. (1921). New York: William Wood and Co. The Urinary Bladder

Keith, A. (1902) Human Embryology and Morphology. London: Edward Arnold. The Uro-genital System


  1. L A Favorito, H M Pazos, S F Costa, W S Costa, F J Sampaio Morphology of the fetal bladder during the second trimester: Comparing genders. J Pediatr Urol: 2014; PubMed 25434295
  2. 2.0 2.1 Syed S Islam, Reza Bayat Mokhtari, Sushil Kumar, Joe Maalouf, Sara Arab, Herman Yeger, Walid A Farhat Spatio-temporal distribution of Smads and role of Smads/TGF-β/BMP-4 in the regulation of mouse bladder organogenesis. PLoS ONE: 2013, 8(4);e61340 PubMed 23620745
  3. Stacy T Tanaka, Kenichiro Ishii, Romano T Demarco, John C Pope, John W Brock, Simon W Hayward Endodermal origin of bladder trigone inferred from mesenchymal-epithelial interaction. J. Urol.: 2010, 183(1);386-91 PubMed 19914648 PMC2794964 | J Urol.
  4. Sahar N Saleem Fetal MRI: An approach to practice: A review. J Advanc Res: 2014, 5(5);507-23 PubMed 25685519 | J Adv Res.
  5. Vishal Gajbhiye, Sasanka Nath, Priya Ghosh, Argha Chatterjee, Dipanjan Haldar, Sukanta K Das Complete duplication of the urinary bladder: An extremely rare congenital anomaly. Urol Ann: 2013, 7(1);91-3 PubMed 25657554 | Urol Ann.


Ellen Shapiro Clinical implications of genitourinary embryology. Curr Opin Urol: 2009, 19(4);427-33 PubMed 19461520

Andrea Brenner-Anantharam, Cristina Cebrian, Richard Guillaume, Romulo Hurtado, Tung-Tien Sun, Doris Herzlinger Tailbud-derived mesenchyme promotes urinary tract segmentation via BMP4 signaling. Development: 2007, 134(10);1967-75 PubMed 17442697

Frank Costantini Renal branching morphogenesis: concepts, questions, and recent advances. Differentiation: 2006, 74(7);402-21 PubMed 16916378

Search Bookshelf bladder development | trigone development ureter development


Renata Viana, Ekatherina Batourina, Hongying Huang, Gregory R Dressler, Akio Kobayashi, Richard R Behringer, Ellen Shapiro, Terry Hensle, Sarah Lambert, Cathy Mendelsohn The development of the bladder trigone, the center of the anti-reflux mechanism. Development: 2007, 134(20);3763-9 PubMed 17881488

Search PubMed

Search Pubmed: urinary bladder development | bladder development


  • bladder exstrophy - A congenital malformation with bladder open to ventral wall of abdomen (between umbilicus and pubic symphysis) and may have other anomolies associated with failure of closure of abdominal wall and bladder (epispadias, pubic bone anomolies).
  • hydronephrosis - (congenital hydronephrosis, Greek, hydro = water) A kidney abnormality due to partial or complete obstruction at the pelvi-ureteric junction. This leads to a grossly dilated renal pelvis causing extensive renal damage before birth.
  • mesonephric duct - (= Wollfian duct) An early developing urogenital duct running the length of the embryo that will differentiate and form the male reproductive duct system. In females this duct degenerates (some remnants may remain associated in broad ligament).
  • proteinuria - The abnormal presence of protein in the urine and an indicator of diesease including diabetic kidney disease (DKD, diabetic nephropathy).
  • renal - (Latin, renes = kidney) Term used in relation to the kidney and associated structures (renal pelvis, renal artery)
  • ureter - The two ureters are hollow tubes that link and carries urine from kidney to the bladder. The tubes have a muscular wall lined with transitional epithelium.
  • urethra - The single muscular tube that links and carries urine from the bladder to the exterior. In humans, the urethral length differs between the sexes (male longer, female shorter).
  • urinary - Term used to describe all components of the kidney system including the bladder, ureters and urethra.
  • urine - Term used to describe the liquid waste produced by the kidney, stored in the bladder and excreted from teh body through the urethra.
  • urorectal septum - (URS) The structure which develops to separate the cloaca (common urogenital sinus) into an anterior urinary part and a posterior rectal part.
  • Wolffian duct - (= mesonephric duct, preferred terminology), runs from the mesonephros to cloaca, differentiates to form the male vas deferens and in the female regresses. Named after Caspar Friedrich Wolff (1733-1794), a German scientist and early embryology researcher and is said to have established the doctrine of germ layers. (More? Caspar Friedrich Wolff)

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Cite this page: Hill, M.A. 2018 Embryology Urinary Bladder Development. Retrieved January 19, 2018, from https://embryology.med.unsw.edu.au/embryology/index.php/Urinary_Bladder_Development

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© Dr Mark Hill 2018, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G