BGDB Sexual Differentiation - Fetal: Difference between revisions
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[[Prostate Development]] | [[Prostate Development]] | ||
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| [[File:Nephron development 01.jpg|600px]] | |||
Nephron development <ref name=PMID23338209><pubmed>23338209</pubmed><ref> | |||
| The morphological events and localization of renal progenitors occurring during nephron development in the adult human kidney. | |||
Mesenchymal cells near the tips of the branching ureteric bud undergo epithelial transition and differentiate through a series of forms made up of renal progenitors (red) | |||
* '''a''' - condensed aggregate forms | |||
* '''b''' - renal vesicle forms | |||
* '''c''' - S-shaped body (red), renal progenitors are localised, at this stage podocyte-committed progenitors (red + blue) as well as tubular-committed progenitors (orange) can already be seen. | |||
* '''d''' - mature nephron, renal progenitors (red), podocyte-committed progenitors (red + blue), as well as tubular-committed progenitors (orange) are distributed along the nephron. | |||
* '''e''' - glomerulus, renal progenitors (red) are localized at the urinary pole of the Bowman capsule. Podocyte-committed progenitors (red + blue) localize along the Bowman capsule. | |||
Revision as of 13:45, 6 June 2017
Practical 12: Sex Determination | Early Embryo | Late Embryo | Fetal | Postnatal | Abnormalities | 2011 Audio |
Introduction
In the previous section we observed late embryonic male genital development and now in fetal development we will observe early fetal female development. Then we will explore fetal development of the external genitalia and gonadal descent.
Week 10 Female
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Plane A (most lateral) | Plane B (lateral) |
Plane C (medial) | Plane D (midline) |
Uterus and Vagina
Mouse paramesonephric duct (Müllerian duct)[1] |
This mouse image shows the relationship between the mesonephric and paramesonephric ducts opening into the urogenital sinus.
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Female Uterus and Vagina (between week 9 and 20) | |
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<html5media height="500" width="490">File:Uterus_002.mp4</html5media> | Note - the entire vagina is formed from the paramesonephric (Müllerian) duct and does not have a contribution from the urogenital endoderm.
The uterus and broad ligament will eventulaly divide the pelvic cavity into two separate pouches.
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This graph shows the growth during the fetal period of the uterus between week 19 and 38.[2]
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External Genitalia
This next section will look at the development of the external genitalia using a series of animations and online resources.
Female External Genitalia
<html5media height="380" width="270">File:Female_external_001.mp4</html5media> | Animation showing the development of external female genitalia from the indifferent external structure (week 9 to 12 approximately).
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Male External Genitalia
<html5media height="380" width="270">File:Male_external_001.mp4</html5media> | Animation showing the development of external male genitalia from the indifferent external structure (week 9 to 12 approximately).
The reduction of Testosterone to active metabolite, 5α-dihydrotestosterone (DHT) is carried out by the enzyme 5α-reductase expressed in the region or male external genitaila and prostate gland. Note that there are several 5α-reductase isoforms that differ in both tissue distribution and kinetics.
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External Genitalia Comparison
Gonad Descent
<html5media height="430" width="300">File:Gonad blood 01.mp4</html5media> | Animation shows the descent of the gonads and their blood supply.
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Internal Gonad Descent
Testes Descent
Embryology - 15 Jun 2024 Expand to Translate |
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<html5media height="400" width="600">File:Testis_Descent_001.mp4</html5media> | The animation shows the descent of the testes (between week 7 to 38, birth).
Descent of the testes into the scrotal sac begins generally during week 26 and may take several days.
Incomplete or failed descent can occur unilaterally or bilaterally, is more common in premature births, and can be completed postnatally. (see also cryptorchidism). |
Data from a study of male human fetal (between 10 and 35 weeks) gonad position[3]
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Fetal Kidney
Nephrogenesis is the formation of the functional nephron occurs in the fetal period with all of the nephrons formed by 30 to 34 weeks (GA 32 to 36 weeks). There are no new nephrons formed after this period.
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Adult Nephron Structure |
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. |
Testes Descent Timeline
Data from a study of male human fetal (between 10 and 35 weeks) gonad position.[3]
- 10 to 23 weeks - (9.45%) had migrated from the abdomen and were situated in the inguinal canal
- 24 to 26 weeks - (57.9%) had migrated from the abdomen
- 27 to 29 weeks - (16.7%) had not descended to the scrotum
A second study looked at the position of the testes[4]
- 33 weeks fetal testes had descended to the scrotum
- between 33 to 40 weeks (term) both testes have normally descended to the scrotum
Failure of descent (cryptorchidism) either unilateral or bilateral testicular descent, occurring in up to 30% premature and 3-4% term males.
Cryptorchidism in common eutherian mammals.[5]- Species comparison of descent timeline
Prostate
Under the influence the gonad-derived fetal testosterone acting through androgen receptors, a region of the urogenital sinus mesenchyme differentiates to form the primordial prostate buds. The buds then signal back to the overlying epithelium, inducing duct formation.
Renal Stages
Nephron development <ref name=PMID23338209><pubmed>23338209</pubmed><ref> |
The morphological events and localization of renal progenitors occurring during nephron development in the adult human kidney.
Mesenchymal cells near the tips of the branching ureteric bud undergo epithelial transition and differentiate through a series of forms made up of renal progenitors (red)
Glomerulus StructureHyperfiltration HypothesisDevelopmental renal mass reduction could result in glomerular alterations that may have adverse effects in long-term renal health. There are also no easy methods to easily detect a reduced nephron reserve. <pubmed>8743495</pubmed> <pubmed>22532329</pubmed> Historic Genital Images
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
Cite this page: Hill, M.A. (2024, June 15) Embryology BGDB Sexual Differentiation - Fetal. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/BGDB_Sexual_Differentiation_-_Fetal
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