Cloaca Development: Difference between revisions
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* '''The development of the cloaca in the human embryo'''{{#pmid:30294789|PMID30294789}} "Subdivision of cloaca into urogenital and anorectal passages has remained controversial because of disagreements about the identity and role of the septum developing between both passages. This study aimed to clarify the development of the cloaca using a quantitative 3D morphological approach in human embryos of 4-10 post-fertilisation weeks. ...Our main finding was a pronounced difference in growth between rapidly expanding central and ventral parts, and slowly or non-growing cranial and dorsal parts. The entrance of the Wolffian duct into the cloaca proved a stable landmark that remained linked to the position of vertebra S3. Suppressed growth in the cranial cloaca resulted in an apparent craniodorsal migration of the entrance of the Wolffian duct, while suppressed growth in the dorsal cloaca changed the entrance of the hindgut from cranial to dorsal on the cloaca. Transformation of this 'end-to-end' into an 'end-to-side' junction produced temporary 'lateral (Rathke's) folds'. The persistent difference in dorsoventral growth straightened the embryonic caudal body axis and concomitantly extended the frontally oriented 'urorectal (Tourneux's) septum' caudally between the ventral urogenital and dorsal anorectal parts of the cloaca. The dorsoventral growth difference also divided the cloacal membrane into a well-developed ventral urethral plate and a thin dorsal cloacal membrane proper, which ruptured at 6.5 weeks. The expansion of the pericloacal mesenchyme followed the dorsoventral growth difference and produced the genital tubercle. Dysregulation of dorsal cloacal development is probably an important cause of anorectal malformations: too little regressive development may result in anorectal agenesis, and too much regression in stenosis or atresia of the remaining part of the dorsal cloaca." (see also historic [[Paper - The development of the cloaca in human embryos|1911 | * '''The development of the cloaca in the human embryo'''{{#pmid:30294789|PMID30294789}} "Subdivision of cloaca into urogenital and anorectal passages has remained controversial because of disagreements about the identity and role of the septum developing between both passages. This study aimed to clarify the development of the cloaca using a quantitative 3D morphological approach in human embryos of 4-10 post-fertilisation weeks. ...Our main finding was a pronounced difference in growth between rapidly expanding central and ventral parts, and slowly or non-growing cranial and dorsal parts. The entrance of the Wolffian duct into the cloaca proved a stable landmark that remained linked to the position of vertebra S3. Suppressed growth in the cranial cloaca resulted in an apparent craniodorsal migration of the entrance of the Wolffian duct, while suppressed growth in the dorsal cloaca changed the entrance of the hindgut from cranial to dorsal on the cloaca. Transformation of this 'end-to-end' into an 'end-to-side' junction produced temporary 'lateral (Rathke's) folds'. The persistent difference in dorsoventral growth straightened the embryonic caudal body axis and concomitantly extended the frontally oriented 'urorectal (Tourneux's) septum' caudally between the ventral urogenital and dorsal anorectal parts of the cloaca. The dorsoventral growth difference also divided the cloacal membrane into a well-developed ventral urethral plate and a thin dorsal cloacal membrane proper, which ruptured at 6.5 weeks. The expansion of the pericloacal mesenchyme followed the dorsoventral growth difference and produced the genital tubercle. Dysregulation of dorsal cloacal development is probably an important cause of anorectal malformations: too little regressive development may result in anorectal agenesis, and too much regression in stenosis or atresia of the remaining part of the dorsal cloaca." (see also historic [[Paper - The development of the cloaca in human embryos|1911 paper]]) | ||
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==Movies== | ==Movies== |
Revision as of 13:03, 14 November 2018
Embryology - 23 May 2024 Expand to Translate |
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Introduction
The initial cloaca is the common early endoderm lined space of the hindgut that will later become partitioned by a septum into a dorsal gastrointestinal component (rectum) and ventral renal/genital component (urogenital sinus). Note that the cloaca in mammals is an early embryonic transient structure and only persists in birds and reptiles. Located at the superior end of the cloaca is the allantois, that extends into the connecting stalk and later the placental cord. Located at the inferior end of the cloaca is the cloacal membrane, that also forms part of the embryo surface.
The gastrointestinal tract ends at this cloacal membrane, equivalent to the beginning of the tract at the buccopharyngeal membrane at the upper end. The cloacal membrane is formed during gastrulation by ectoderm and endoderm without a middle (intervening) layer of mesoderm, that later degenerates after cloacal septation.
The hindgut component will contribute to the gastrointestinal tract intestine of the distal transverse colon, descending colon, sigmoid colon, rectum.
The urogenital sinus component will contribute the renal urinary bladder and participate in genital development.
Some Recent Findings
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More recent papers |
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This table allows an automated computer search of the external PubMed database using the listed "Search term" text link.
More? References | Discussion Page | Journal Searches | 2019 References | 2020 References Search term: Cloaca <pubmed limit=5>Cloaca</pubmed>
<pubmed limit=5>Cloacal Membrane</pubmed> |
Older papers |
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These papers originally appeared in the Some Recent Findings table, but as that list grew in length have now been shuffled down to this collapsible table.
See also the Discussion Page for other references listed by year and References on this current page. |
Movies
Early Endoderm | Week 3 Folding |
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<html5media height="400" width="350">File:Amnion 001.mp4</html5media> | <html5media height="500" width="350">File:Week3_folding.mp4</html5media> |
- Links: Early Endoderm Movie | Week 3 Folding Movie
Development
Stage 10
Caudal end of embryo showing primitive streak region, cloacal membrane, and connecting stalk. |
- Links: Carnegie stage 10 | Stage 10 Movie
Stage 11
Historic image<ref name=Low1908>Low A. Description of a human embryo of 13-14 mesodermic somites. (1908) J Anat Physiol. 42(3): 237-51. PMID 17232769 | PMC1289161 of an embryo model (sagittal section, viewed from the left) showing hindgut and cloaca. |
- Links: Carnegie stage 11
Stage 12
- ===Stage 13===
- ===Stage 22===
- ==Abnormalities==
- ===Persistent Cloaca Perineum===
- ==References==
- ===Books===
- ===Reviews===
- ===Articles===
- ===Historic===
- ===Search Pubmed===
- ==Additional Images==
- ===Historic===
Terms
Gastrointestinal Tract Terms | ||
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Glossary Links
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Cite this page: Hill, M.A. (2024, May 23) Embryology Cloaca Development. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Cloaca_Development
- © Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G