BGDB Sexual Differentiation - Early Embryo: Difference between revisions
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| '''Stages in septation of the urogenital sinus between Week 4 and 6.''' | | '''Stages in septation of the urogenital sinus between Week 4 and 6.''' | ||
The initial cloaca is divided by the urorectal septum. The posterior portion forms the rectum and the anterior portion forms the primitive urogenital sinus. The superior part of the primitive urogenital sinus forms the urinary bladder, this and the rectum are the same for both sexes. The inferior part of the primitive urogenital sinus forms different structures in males and females. The constricting part forms the prostatic urethra (male) or the membranous urethra (female), beneath this region the expanded space is the definitive urogenital sinus forms the penile urethra (male) or vagina vestibule (female). Note the animation is simplified, as the cloacal membrane appears to break down before the septum can fuse with it. | * The initial cloaca is divided by the urorectal septum. | ||
* The posterior portion forms the rectum and the anterior portion forms the primitive urogenital sinus. | |||
* The superior part of the primitive urogenital sinus forms the urinary bladder, this and the rectum are the same for both sexes. | |||
* The inferior part of the primitive urogenital sinus forms different structures in males and females. The constricting part forms the prostatic urethra (male) or the membranous urethra (female), beneath this region the expanded space is the definitive urogenital sinus forms the penile urethra (male) or vagina vestibule (female). Note the animation is simplified, as the cloacal membrane appears to break down before the septum can fuse with it. | |||
Several different defects in both sexes can occur if this septation process is not correctly aligned (rectourethral fistula, rectovaginal fistula). | Several different defects in both sexes can occur if this septation process is not correctly aligned (rectourethral fistula, rectovaginal fistula). |
Revision as of 15:08, 2 June 2011
Practical 12: Sex Determination | Early Embryo | Late Embryo | Fetal | Postnatal | Abnormalities | 2011 Audio |
Week 4 to 5
<wikiflv width="560" height="588" autoplay="true" position="left">Stage13_GITlarge.flv|File:Stage13-GIT-icon.jpg</wikiflv> |
Begin by observing the internal structure of the embryo at the end of week 4 and the beginning of week 5.
Colour code:
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Mesonephros and Mesonephric Duct
E1-G4: Section passes dorsally to the mesonephros. Return to G4 and then follow the caudal route of the mesonephric duct into the sacral region.
E1L | E2L | E3L | E4L | E5L | E6L | E7L |
F1L | F2L | F3L | F4L | F5L | F6L | F7L |
G1L | G2L | G3L | G4L |
Kidney and Mesonephric Duct
<wikiflv width="356" height="500" autoplay="true" position="left">Urogenital_sinus_001.flv|File:Urogenital_sinus_001 icon.jpg</wikiflv> |
Now go back and observe the development of the intermediate mesoderm.
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Primitive Urogenital Sinus
Gonad Development
Male Testis
Female Ovary
Gonadal Development Comparison
Now directly compare the development of the male and female gonad (click image to start, these may not be synchronised).
Gonad-icon.jpg</wikiflv> | Gonad-icon.jpg</wikiflv> |
Ovary | Testis |
Practical 12: Sex Determination | Early Embryo | Late Embryo | Fetal | Postnatal | Abnormalities | 2011 Audio |
Additional Information
The following figures are from a recent review of Sex determination and gonadal development in mammals.[1]
- Signaling in genital development
- Sex reversal in humans caused by abnormal X-Y exchange
- Mesonephric tubules in the 11.5 dpc mouse urogenital ridge
- Development and differentiation of the genital duct system
- The migratory pathway of primordial germ cells
- Structure of the early fetal testis
- Differentiation of pre-Sertoli cells into Sertoli cells
- Model for cell-autonomous and prostaglandin-mediated upregulation of Sox9 in pre-Sertoli cells
- Visualization of testicular cell types
- Ovary and follicle development and differentiation
- Postulated molecular pathway leading to the formation of the bipotential genital ridge
- Structure of mouse and human SRY protein
- Postulated interaction of molecular players involved in early testicular development
References
- ↑ <pubmed>17237341</pubmed>| Physiol. Rev.
Nussey S, Whitehead S. Endocrinology: An Integrated Approach. Oxford: BIOS Scientific Publishers; 2001. Chapter 6 The gonad
BGDB: Lecture - Gastrointestinal System | Practical - Gastrointestinal System | Lecture - Face and Ear | Practical - Face and Ear | Lecture - Endocrine | Lecture - Sexual Differentiation | Practical - Sexual Differentiation | Tutorial
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Cite this page: Hill, M.A. (2024, June 3) Embryology BGDB Sexual Differentiation - Early Embryo. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/BGDB_Sexual_Differentiation_-_Early_Embryo
- © Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G