BGDB Sexual Differentiation - Late Embryo: Difference between revisions
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[[Media:Trigone_001.mp4|'''Click Here''' to play on mobile device]] | [[Media:Trigone_001.mp4|'''Click Here''' to play on mobile device]] | ||
| This animation shows the | | This animation shows the historic interpretation of trigone development between Week 4 and 6. (See | ||
* The mesonephric duct (purple) has lateral branches forming the uteric bud (kidney) | * The mesonephric duct (purple) has lateral branches forming the uteric bud (kidney) | ||
* both these fuse into the wall of the bladder (yellow). | * both these fuse into the wall of the bladder (yellow). | ||
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{{Genital Links}} | {{Genital Links}} | ||
===Trigone=== | |||
The dorsal bladder region bounded by the 2 ureters and the urethra form the region known as the trigone. The classical embryology description of the origin of this region was from the mesonephric duct (Wolffian duct), as shown in this animation. | |||
More recent mouse studies suggest that this bladder region is endodermal and not mesodermal in origin.<ref name="PMID19914648"><pubmed>19914648</pubmed></ref> Using a similar mouse model, this trigone embryonic region appears to contain most of the bladder progenitor cells.<ref name="PMID24992712"><pubmed>24992712</pubmed></ref> Any mesonephric duct (Wolffian duct) located in the mouse trigone region appears to be developmentally lost by apoptosis.<ref><pubmed>19568352</pubmed></ref> | |||
In contrast, the prostatic central zone, seminal vesicle, and ejaculatory ducts all originate from the mesonephric duct (Wolffian duct).<ref name="PMID20413145"><pubmed>20413145</pubmed></ref> | |||
==References== | ==References== |
Revision as of 09:33, 31 May 2016
Practical 12: Sex Determination | Early Embryo | Late Embryo | Fetal | Postnatal | Abnormalities | 2011 Audio |
Week 8
<html5media height="500" width="505">File:Stage22_URG3d.mp4</html5media>
Click Here to play on mobile device Week 8, Carnegie stage 22, male. Page |
Begin by observing the internal structure of the embryo at the end of week 8.
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G5 urogenital | urogenital |
Embryo (week 8, Stage 22) Renal
Urinary System Development
Development of the Urinary Bladder
<html5media height="500" width="360">File:Urogenital_sinus_001.mp4</html5media> | <html5media height="415" width="420">File:Urogenital_septum_001.mp4</html5media> | Division of the Cloaca
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Development of the Urethra
Further development of the urinary system outflow tract, the urethra, varies depending on the sex of the embryo.
- Males - the pelvic urethra forms the membranous urethra, the prostatic urethra and penile urethra. (The sex of the above animation and sections is male)
- Females - the pelvic urethra forms the membranous urethra and the vestibule of the vagina.
Development of the Kidney
<html5media height="280" width="400">File:Nephron_development.mp4</html5media> |
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<mediaplayer width='295' height='430' image="http://php.med.unsw.edu.au/embryology/images/7/71/Renal_blood_01_icon.jpg">File:Renal blood 01.mp4</mediaplayer> |
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Genital System Development
Male
peritoneal cavity | rete tesits | G3 testis |
- week 8 - males Sertoli cells secrete anti müllerian hormone (AMH), which causes regression of the paramesonephric ducts between the 8th and 10th weeks.
- week 9 to 10 - gonadal cells begin to produce testosterone, which maintains the mesonephric ducts.
- mesonephric ducts go on to form the internal genital tract:
- rete testis
- ductuli efferentes
- vas deferens
Female
- during the same time course as above, the opposite occurs.
- The sex cords degenerate and the genital ridge forms secondary cortical sex cords.
- These induce the primordial germ cells to form the ovarian follicles.
- Due to the lack of AMH and testosterone, the mesonephric ducts degenerate
Paramesonephric (Müllerian) ducts form the internal female genital tract
In both sexes, the external genitalia appear similar until week 12 (GA week 14).
Trigone
<html5media height="380" width="450">File:Trigone_001.mp4</html5media> | This animation shows the historic interpretation of trigone development between Week 4 and 6. (See
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Practical 12: Sex Determination | Early Embryo | Late Embryo | Fetal | Postnatal | Abnormalities | 2011 Audio |
Additional Information
Additional Information - Content shown under this heading is not part of the material covered in this class. It is provided for those students who would like to know about some concepts or current research in topics related to the current class page. |
Trigone
The dorsal bladder region bounded by the 2 ureters and the urethra form the region known as the trigone. The classical embryology description of the origin of this region was from the mesonephric duct (Wolffian duct), as shown in this animation.
More recent mouse studies suggest that this bladder region is endodermal and not mesodermal in origin.[1] Using a similar mouse model, this trigone embryonic region appears to contain most of the bladder progenitor cells.[2] Any mesonephric duct (Wolffian duct) located in the mouse trigone region appears to be developmentally lost by apoptosis.[3]
In contrast, the prostatic central zone, seminal vesicle, and ejaculatory ducts all originate from the mesonephric duct (Wolffian duct).[4]
References
BGDB: Lecture - Gastrointestinal System | Practical - Gastrointestinal System | Lecture - Face and Ear | Practical - Face and Ear | Lecture - Endocrine | Lecture - Sexual Differentiation | Practical - Sexual Differentiation | Tutorial
Glossary Links
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Cite this page: Hill, M.A. (2024, March 28) Embryology BGDB Sexual Differentiation - Late Embryo. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/BGDB_Sexual_Differentiation_-_Late_Embryo
- © Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G