BGDB Sexual Differentiation - Late Embryo: Difference between revisions
From Embryology
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==Urinary System Development== | ==Urinary System Development== | ||
===Development of the Urinary Bladder=== | ===Development of the Urinary Bladder=== | ||
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* Males - the pelvic urethra forms the membranous urethra, the prostatic urethra and penile urethra. (The sex of the above animation and sections is male) | * 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. | * Females - the pelvic urethra forms the membranous urethra and the vestibule of the vagina. | ||
===Development of the Kidney=== | |||
* The adult kidneys (the metanephroi) form from day 35, from a portion of the intermediate mesoderm called the metanephric blastema (or metanephric mesenchyme). | |||
* They are induced to form by the ureteric buds, outgrowths from the end of the mesonephric ducts, which come into contact with the metanephric blastema. | |||
* 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. | |||
**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. | |||
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| <qt>file=Renal blood 01.mov|width=296px|height=450px|controller=true|autoplay=false</qt> | |||
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* starts in week 5 and is completed by week 15. | |||
* week 6 - the kidneys begin to change their relative position, described as "ascent of the kidneys", to their correct anatomical position. | |||
* week 9 - the rising movement is completed. | |||
* During the ascent, the kidneys also become vascularised via the dorsal aorta. | |||
* As this ascent occurs, the mesonephric ducts and the ureters enter the wall of the developing bladder. | |||
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==Genital System Development== | ==Genital System Development== |
Revision as of 11:27, 27 May 2012
Practical 12: Sex Determination | Early Embryo | Late Embryo | Fetal | Postnatal | Abnormalities | 2011 Audio |
Week 8
<wikiflv width="560" height="588" autoplay="true" position="left">Stage22_urogenlarge.flv|File:Stage22-UG-icon.jpg</wikiflv> (Carnegie stage 22, male) Quicktime |
Begin by observing the internal structure of the embryo at the end of week 8.
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Embryo (week 8, Stage 22) Renal
Urinary System Development
Development of the Urinary Bladder
width=348px|height=490px|controller=true|autoplay=false</qt> | width=350px|height=360px|controller=true|autoplay=false</qt> | Division of the Cloaca
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Development of the Urethra
- Further development of the urinary system 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
- The adult kidneys (the metanephroi) form from day 35, from a portion of the intermediate mesoderm called the metanephric blastema (or metanephric mesenchyme).
- They are induced to form by the ureteric buds, outgrowths from the end of the mesonephric ducts, which come into contact with the metanephric blastema.
- 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.
- 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.
width=296px|height=450px|controller=true|autoplay=false</qt> |
|
Genital System Development
Male
G3 testis | G4 rete tesits |
- 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 ducts go on to form the internal genital tract:
- uterine (fallopian) tubes
- uterus body
- vagina
In both sexes, the external genitalia appear similar until the 12th week.
Trigone
G5 urogenital | G6 urogenital | G7 urogenital |
Practical 12: Sex Determination | Early Embryo | Late Embryo | Fetal | Postnatal | Abnormalities | 2011 Audio |
Additional Information
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 25) 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