BGDB Sexual Differentiation - Late Embryo: Difference between revisions
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* '''Females''' - the pelvic urethra forms the membranous urethra and the vestibule of the vagina. | * '''Females''' - the pelvic urethra forms the membranous urethra and the vestibule of the vagina. | ||
===Development of the Kidney=== | ===Early Development of the Kidney=== | ||
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| width=420px|<html5media height="280" width="400">File:Nephron_development.mp4</html5media> | | width=420px|<html5media height="280" width="400">File:Nephron_development.mp4</html5media> | ||
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* | * Adult kidneys (the metanephroi) form from day 35, from a portion of the intermediate mesoderm called the metanephric blastema (or metanephric mesenchyme). | ||
* | * Ureteric buds, outgrowths from the end of the mesonephric ducts, induce the metanephric blastema. | ||
* Upon contact, they begin to lengthen and bifurcate rapidly in the metanephric blastema – these branches differentiate into the collecting ducts. | * Upon contact, they begin to lengthen and bifurcate rapidly in the metanephric blastema – these branches differentiate into the collecting ducts. | ||
* Both the ureteric buds and the metanephric blastema begin to differentiate; interestingly each induces differentiation in the other structure. | * Both the ureteric buds and the metanephric blastema begin to differentiate; interestingly each induces differentiation in the other structure. | ||
** The ureteric bud is induced by the metanephric blastema to form the collecting tubules, renal pelvis and ureters. | ** The ureteric bud is induced by the metanephric blastema to form the collecting tubules, renal pelvis and ureters. | ||
** The metanephric blastema is induced to form the nephrons. | ** The metanephric blastema is induced to form the nephrons. | ||
'''Nephrogenesis''' - the formation of the nephron (shown in the second part of this animation) occurs in the fetal period with all of the nephrons formed by 30 to 34 weeks ({{GA}} 32 to 36 weeks). | |||
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Revision as of 11:07, 31 May 2016
Practical 12: Sex Determination | Early Embryo | Late Embryo | Fetal | Postnatal | Abnormalities | 2011 Audio |
Week 8
<html5media height="520" 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.
Early Development of the Kidney
<html5media height="280" width="400">File:Nephron_development.mp4</html5media> |
Nephrogenesis - the formation of the nephron (shown in the second part of this animation) occurs in the fetal period with all of the nephrons formed by 30 to 34 weeks (GA 32 to 36 weeks). |
<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 [[BGDB_Sexual_Differentiation_-_Late_Embryo#Trigone_2|current research on trigone development).
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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]
Seminal Vesicle
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, April 26) 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