Cloaca Development - Revision history

Z8600021 at 04:17, 17 April 2019

2019-04-17T04:17:22Z

← Older revision		Revision as of 14:17, 17 April 2019
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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 paper]])		* '''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]])

	* '''Clarification of mammalian cloacal morphogenesis using high-resolution episcopic microscopy'''{{#pmid:26485363\|PMID26485363}} "The developmental process through which the cloaca transforms from one hollow structure to two separated urinary and digestive outlets remains controversial and speculative. Here, we use high-resolution episcopic microscopy to examine a comprehensive series of normal and mutant {{mouse}} cloaca in which the detailed 3-dimensional (3-D) morphological features are illuminated throughout the development. We provide evidence that the dorsal peri-cloacal mesenchyme (dPCM) remains stationary while other surrounding tissues grow towards it. This causes dramatic changes of spatial relationship among caudal structures and morphological transformation of the cloaca. The 3-D characterizations of Dkk1 mutants reveal a hyperplastic defect of dPCM, which leads to a significant anterior shift of the caudal boundary of the cloaca, premature occlusion of the cloaca and, imperforate anus phenotype. Conversely, {{Shh}} knockout causes a severe hypoplastic defect of cloaca mesenchyme including dPCM and persistent cloaca. Collectively, these findings suggest that formation of the dPCM is critical for cloacal morphogenesis and furthermore, growth and movement of the mesenchymal tissues towards the dPCM lead to the cloaca occlusion and separation of the urinary and digestive outlets."

	\|}		\|}
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	\| [[File:Mark_Hill.jpg\|90px\|left]] {{Most_Recent_Refs}}		\| [[File:Mark_Hill.jpg\|90px\|left]] {{Most_Recent_Refs}}

	Search term: [http://www.ncbi.nlm.nih.gov/pubmed/?term=Cloaca ''Cloaca'']		Search term: [http://www.ncbi.nlm.nih.gov/pubmed/?term=Cloaca ''Cloaca''] \| [http://www.ncbi.nlm.nih.gov/pubmed/?term=Cloacal+Membrane ''Cloacal Membrane'']

	~~<pubmed limit=5>Cloaca</pubmed>~~
	~~<br>~~
	~~Search term: [http://www.ncbi.nlm.nih.gov/pubmed/?term=Cloacal+Membrane ''Cloacal Membrane'']~~

	~~<pubmed limit=5>Cloacal Membrane</pubmed>~~
	\|}		\|}
	{\| class="wikitable mw-collapsible mw-collapsed"		{\| class="wikitable mw-collapsible mw-collapsed"
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	\|-		\|-
	\| {{Older papers}}		\| {{Older papers}}
			* '''Clarification of mammalian cloacal morphogenesis using high-resolution episcopic microscopy'''{{#pmid:26485363\|PMID26485363}} "The developmental process through which the cloaca transforms from one hollow structure to two separated urinary and digestive outlets remains controversial and speculative. Here, we use high-resolution episcopic microscopy to examine a comprehensive series of normal and mutant {{mouse}} cloaca in which the detailed 3-dimensional (3-D) morphological features are illuminated throughout the development. We provide evidence that the dorsal peri-cloacal mesenchyme (dPCM) remains stationary while other surrounding tissues grow towards it. This causes dramatic changes of spatial relationship among caudal structures and morphological transformation of the cloaca. The 3-D characterizations of Dkk1 mutants reveal a hyperplastic defect of dPCM, which leads to a significant anterior shift of the caudal boundary of the cloaca, premature occlusion of the cloaca and, imperforate anus phenotype. Conversely, {{Shh}} knockout causes a severe hypoplastic defect of cloaca mesenchyme including dPCM and persistent cloaca. Collectively, these findings suggest that formation of the dPCM is critical for cloacal morphogenesis and furthermore, growth and movement of the mesenchymal tissues towards the dPCM lead to the cloaca occlusion and separation of the urinary and digestive outlets."
	\|}		\|}

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	\|}		\|}
	:'''Links:''' [[Carnegie stage 10]] \| [[Model Embryo 3.1mm Movie 1\|Stage 10 Movie]]		:'''Links:''' [[Carnegie stage 10]] \| [[Model Embryo 3.1mm Movie 1\|Stage 10 Movie]]

	===Stage 11===		===Stage 11===
	{\|		{\|

Z8600021 at 05:47, 14 November 2018

2018-11-14T05:47:04Z

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	{{#pmid:14444236}}		{{#pmid:14444236}}

			{{Ref-PrentissArey1918}} [[Book_-_A_Laboratory_Manual_and_Text-book_of_Embryology_8#Differentiation_of_Cloaca.2C_Bladder.2C_Urethra_and_Urogenital_Sinus\|Differentiation of Cloaca, Bladder, Urethra and Urogenital Sinus]]

	{{Ref-Felix1912}}		{{Ref-Felix1912}}

Z8600021 at 05:33, 14 November 2018

2018-11-14T05:33:28Z

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	===Stage 22===		===Stage 22===

			==Animal Model==

			See this recent analysis of {{mouse}} cloacal morphogenesis using high-resolution episcopic microscopy.{{#pmid:26485363\|PMID26485363}}
			* [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4688061/bin/NIHMS734311-supplement-2.mp4 Video 1. Figure S2.] The 3-D images of the entire mouse cloaca morphogenetic process from {{ME9.5}} to {{ME13.5}}.

	==Molecular==		==Molecular==

Z8600021 at 05:24, 14 November 2018

2018-11-14T05:24:34Z

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	{{Header}}		'''Bold text'''{{Header}}
	==Introduction==		==Introduction==
	[[File:Stage12 sem9 cloacal membrane.jpg\|alt=Carnegie stage 12 cloacal membrane\|thumb\|Human Embryo stage {{CS12}} cloacal membrane (SEM}]]		[[File:Stage12 sem9 cloacal membrane.jpg\|alt=Carnegie stage 12 cloacal membrane\|thumb\|Human Embryo stage {{CS12}} cloacal membrane (SEM}]]
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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 paper]])		* '''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]])

			* '''Clarification of mammalian cloacal morphogenesis using high-resolution episcopic microscopy'''{{#pmid:26485363\|PMID26485363}} "The developmental process through which the cloaca transforms from one hollow structure to two separated urinary and digestive outlets remains controversial and speculative. Here, we use high-resolution episcopic microscopy to examine a comprehensive series of normal and mutant {{mouse}} cloaca in which the detailed 3-dimensional (3-D) morphological features are illuminated throughout the development. We provide evidence that the dorsal peri-cloacal mesenchyme (dPCM) remains stationary while other surrounding tissues grow towards it. This causes dramatic changes of spatial relationship among caudal structures and morphological transformation of the cloaca. The 3-D characterizations of Dkk1 mutants reveal a hyperplastic defect of dPCM, which leads to a significant anterior shift of the caudal boundary of the cloaca, premature occlusion of the cloaca and, imperforate anus phenotype. Conversely, {{Shh}} knockout causes a severe hypoplastic defect of cloaca mesenchyme including dPCM and persistent cloaca. Collectively, these findings suggest that formation of the dPCM is critical for cloacal morphogenesis and furthermore, growth and movement of the mesenchymal tissues towards the dPCM lead to the cloaca occlusion and separation of the urinary and digestive outlets."

	\|}		\|}
	{\| class="wikitable mw-collapsible mw-collapsed"		{\| class="wikitable mw-collapsible mw-collapsed"
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	===Stage 22===		===Stage 22===

			==Molecular==
			===Sonic Hedgehog===

			In the {{mouse}} model of cloacal development, {{Shh}} knockout causes a severe hypoplastic defect of cloaca mesenchyme including dorsal peri-cloacal mesenchyme and persistent cloaca.{{#pmid:26485363\|PMID26485363}}



			:'''Links:''' {{SHH}}
			===Apoptosis===

			{{apoptosis}} - process of cell death required for the removal of the cloacal membrane.

	==Abnormalities==		==Abnormalities==

Z8600021 at 05:13, 14 November 2018

2018-11-14T05:13:08Z

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	===Cloacal Exstrophy===		===Cloacal Exstrophy===
	{{ICD-11}} [https://icd.who.int/browse11/l-m/en#/http://id.who.int/icd/entity/2004612103 LB17.3 Cloacal exstrophy] a rare (about 1/200,000{{#pmid:19878548\|PMID19878548}}) and complex anorectal and genitourinary malformation in which rectum, vagina and urinary tract share a common everted orifice, accompanied by an {{omphalocele}} and an imperforate anus. Exstrophy of the cloaca is a well-known malformation that includes the persistence and the exstrophy of a cloaca that receives ureters, ileum and a rudimentary hindgut. Cloacal exstrophy is a severe birth defect wherein much of the abdominal organs (the bladder and intestines) are exposed. It often causes the splitting of both male and female ~~feitalia~~ (specifically, the penis and clitoris respectively), and the anus is occasionally sealed.		{{ICD-11}} [https://icd.who.int/browse11/l-m/en#/http://id.who.int/icd/entity/2004612103 LB17.3 Cloacal exstrophy] a rare (about 1/200,000{{#pmid:19878548\|PMID19878548}}) and complex anorectal and genitourinary malformation in which rectum, vagina and urinary tract share a common everted orifice, accompanied by an {{omphalocele}} and an imperforate anus. Exstrophy of the cloaca is a well-known malformation that includes the persistence and the exstrophy of a cloaca that receives ureters, ileum and a rudimentary hindgut. Cloacal exstrophy is a severe birth defect wherein much of the abdominal organs (the bladder and intestines) are exposed. It often causes the splitting of both male and female genitalia (specifically, the penis and clitoris respectively), and the anus is occasionally sealed.


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	===Reviews===		===Reviews===
	{{#pmid:30367985}}		{{#pmid:30367985}}

			{{#pmid:26969227}}

	{{#pmid:25217828}}		{{#pmid:25217828}}

Z8600021 at 04:27, 14 November 2018

2018-11-14T04:27:30Z

← Older revision		Revision as of 14:27, 14 November 2018
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	===Cloacal Exstrophy===		===Cloacal Exstrophy===
	{{ICD-11}} [https://icd.who.int/browse11/l-m/en#/http://id.who.int/icd/entity/2004612103 LB17.3 Cloacal exstrophy] a rare and complex anorectal and genitourinary malformation in which rectum, vagina and urinary tract share a common everted orifice, accompanied by an {{omphalocele}} and an imperforate anus. Exstrophy of the cloaca is a well-known malformation that includes the persistence and the exstrophy of a cloaca that receives ureters, ileum and a rudimentary hindgut. Cloacal exstrophy is a severe birth defect wherein much of the abdominal organs (the bladder and intestines) are exposed. It often causes the splitting of both male and female feitalia (specifically, the penis and clitoris respectively), and the anus is occasionally sealed.		{{ICD-11}} [https://icd.who.int/browse11/l-m/en#/http://id.who.int/icd/entity/2004612103 LB17.3 Cloacal exstrophy] a rare (about 1/200,000{{#pmid:19878548\|PMID19878548}}) and complex anorectal and genitourinary malformation in which rectum, vagina and urinary tract share a common everted orifice, accompanied by an {{omphalocele}} and an imperforate anus. Exstrophy of the cloaca is a well-known malformation that includes the persistence and the exstrophy of a cloaca that receives ureters, ileum and a rudimentary hindgut. Cloacal exstrophy is a severe birth defect wherein much of the abdominal organs (the bladder and intestines) are exposed. It often causes the splitting of both male and female feitalia (specifically, the penis and clitoris respectively), and the anus is occasionally sealed.

Z8600021 at 04:25, 14 November 2018

2018-11-14T04:25:14Z

← Older revision		Revision as of 14:25, 14 November 2018
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	==Abnormalities==		==Abnormalities==
			{{ICD-11}} LB17 Structural developmental anomalies of anal canal
			* [https://icd.who.int/browse11/l-m/en#/http://id.who.int/icd/entity/2131510660 LB17.2 Persistent cloaca]
			* [https://icd.who.int/browse11/l-m/en#/http://id.who.int/icd/entity/2004612103 LB17.3 Cloacal exstrophy]
			* [https://icd.who.int/browse11/l-m/en#/http://id.who.int/icd/entity/2020658461 GC04.19 Combined urinary and rectal fistula including cloaca with severe scar or extensive tissue loss]
			===Persistent Cloaca===
			{{ICD-11}} [https://icd.who.int/browse11/l-m/en#/http://id.who.int/icd/entity/2131510660 LB17.2 Persistent cloaca] is a congenital anomaly in which the intestinal, urinary, and reproductive ducts open into a common cavity, a result of the failure of the urorectal septum to form during prenatal development. They occur exclusively in girls and comprise the most complex defect in the spectrum of anorectal malformations.

	~~===Persistent Cloaca Perineum===~~
	{\|		{\|
	\|+ Persistent Cloaca Perineum{{#pmid:17651510\|PMID17651510}}		\|+ Persistent Cloaca Perineum{{#pmid:17651510\|PMID17651510}}
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	\|}		\|}

	:'''Links:''' [[Gastrointestinal Tract - Abnormalities\|GIT Abnormalities]]		:'''Links:''' [https://icd.who.int/browse11/l-m/en#/http://id.who.int/icd/entity/2131510660 LB17.2 Persistent cloaca] \| [[Gastrointestinal Tract - Abnormalities\|GIT Abnormalities]]

	===Cloacal Exstrophy===		===Cloacal Exstrophy===
			{{ICD-11}} [https://icd.who.int/browse11/l-m/en#/http://id.who.int/icd/entity/2004612103 LB17.3 Cloacal exstrophy] a rare and complex anorectal and genitourinary malformation in which rectum, vagina and urinary tract share a common everted orifice, accompanied by an {{omphalocele}} and an imperforate anus. Exstrophy of the cloaca is a well-known malformation that includes the persistence and the exstrophy of a cloaca that receives ureters, ileum and a rudimentary hindgut. Cloacal exstrophy is a severe birth defect wherein much of the abdominal organs (the bladder and intestines) are exposed. It often causes the splitting of both male and female feitalia (specifically, the penis and clitoris respectively), and the anus is occasionally sealed.


			:'''Links:''' [https://icd.who.int/browse11/l-m/en#/http://id.who.int/icd/entity/2004612103 LB17.3 Cloacal exstrophy]
			===OEIS Complex===
			Omphalocele-Exstrophy-Imperforate Anus-Spinal (OEIS) defects, a combination of defects comprising omphalocele, exstrophy of the cloaca, imperforate anus, and spinal defects.

			OMIM: [https://omim.org/entry/258040 OEIS Complex]

Z8600021 at 04:09, 14 November 2018

2018-11-14T04:09:47Z

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	File:Stage12 sem9.jpg		File:Stage12 sem9.jpg
	File:Stage12 sem9 cloacal membrane.jpg		File:Stage12 sem9 cloacal membrane.jpg
	<gallery>		</gallery>

	:'''Links:''' [[Carnegie stage 12]]		:'''Links:''' [[Carnegie stage 12]]

Z8600021 at 04:09, 14 November 2018

2018-11-14T04:09:03Z

← Older revision		Revision as of 14:09, 14 November 2018
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	\| {{Older papers}}		\| {{Older papers}}
	\|}		\|}

	==Movies==		==Movies==
	{\|		{\|
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	<gallery>		<gallery>
	File:Florian1933 fig01.jpg\|Fig.1		File:Florian1933 fig01.jpg\|Fig.1
	File:Florian1933 ~~fig01~~.jpg\|Fig.2		File:Florian1933 fig02.jpg\|Fig.2
	File:Florian1933 ~~fig01~~.jpg\|Fig.3		File:Florian1933 fig03.jpg\|Fig.3
	File:Florian1933 ~~fig01~~.jpg\|Fig.4		File:Florian1933 fig04.jpg\|Fig.4
	File:Florian1933 ~~fig01~~.jpg\|Fig.5		File:Florian1933 fig05.jpg\|Fig.5
	File:Florian1933 ~~fig01~~.jpg\|Fig.6		File:Florian1933 fig06.jpg\|Fig.6
	File:Florian1933 ~~fig01~~.jpg\|Fig.7		File:Florian1933 fig07.jpg\|Fig.7
	File:Florian1933 ~~fig01~~.jpg\|Fig.8		File:Florian1933 fig08.jpg\|Fig.8
	</gallery>		</gallery>

Z8600021 at 03:41, 14 November 2018

2018-11-14T03:41:30Z

← Older revision		Revision as of 13:41, 14 November 2018
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	==Introduction==		==Introduction==
	[[File:Stage12 sem9 cloacal membrane.jpg\|alt=Carnegie stage 12 cloacal membrane\|thumb\|Human Embryo stage {{CS12}} cloacal membrane (SEM}]]		[[File:Stage12 sem9 cloacal membrane.jpg\|alt=Carnegie stage 12 cloacal membrane\|thumb\|Human Embryo stage {{CS12}} cloacal membrane (SEM}]]
	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 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 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 by {{apoptosis}} after cloacal septation.


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	:'''Links:''' {{cloaca}} \| {{Intestine}} \| {{bladder}} \| {{genital}}		:'''Links:''' {{cloaca}} \| {{Intestine}} \| {{bladder}} \| {{genital}} \| {{apoptosis}}
	:: [[Historic Embryology Papers\|Historic papers]]: [[Paper - The development of the cloaca in human embryos\|1911 human cloaca]] \| [[Book_-_Manual_of_Human_Embryology_19-1#Cloaca.2C_Bladder.2C_Urethra.2C_and_Urogenital_Sinus\|1912 Cloaca, Bladder, Urethra, and Urogenital Sinus]] \| [[Paper - The Early Development of Man, with Special Reference to the Development of the Mesoderm and Cloacal Membrane\|1933 Cloacal Membrane]] \| [[Paper - Congenital hernia into the umbilical cord - two cases, one associated with persistent cloaca\|1938 persistent cloaca]]		:: [[Historic Embryology Papers\|Historic papers]]: [[Paper - The development of the cloaca in human embryos\|1911 human cloaca]] \| [[Book_-_Manual_of_Human_Embryology_19-1#Cloaca.2C_Bladder.2C_Urethra.2C_and_Urogenital_Sinus\|1912 Cloaca, Bladder, Urethra, and Urogenital Sinus]] \| [[Paper - The Early Development of Man, with Special Reference to the Development of the Mesoderm and Cloacal Membrane\|1933 Cloacal Membrane]] \| [[Paper - Congenital hernia into the umbilical cord - two cases, one associated with persistent cloaca\|1938 persistent cloaca]]
	<br>		<br>

← Older revision		Revision as of 14:09, 14 November 2018
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	\| {{Older papers}}		\| {{Older papers}}
	\|}		\|}

	==Movies==		==Movies==
	{\|		{\|
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	<gallery>		<gallery>
	File:Florian1933 fig01.jpg\|Fig.1		File:Florian1933 fig01.jpg\|Fig.1
	File:Florian1933 ~~fig01~~.jpg\|Fig.2		File:Florian1933 fig02.jpg\|Fig.2
	File:Florian1933 ~~fig01~~.jpg\|Fig.3		File:Florian1933 fig03.jpg\|Fig.3
	File:Florian1933 ~~fig01~~.jpg\|Fig.4		File:Florian1933 fig04.jpg\|Fig.4
	File:Florian1933 ~~fig01~~.jpg\|Fig.5		File:Florian1933 fig05.jpg\|Fig.5
	File:Florian1933 ~~fig01~~.jpg\|Fig.6		File:Florian1933 fig06.jpg\|Fig.6
	File:Florian1933 ~~fig01~~.jpg\|Fig.7		File:Florian1933 fig07.jpg\|Fig.7
	File:Florian1933 ~~fig01~~.jpg\|Fig.8		File:Florian1933 fig08.jpg\|Fig.8
	</gallery>		</gallery>