Difference between revisions of "Reproductive System Development"
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==EMBRYOLOGICAL DEVELOPMENT OF THE GENITAL TRACT== | ==EMBRYOLOGICAL DEVELOPMENT OF THE GENITAL TRACT== | ||
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*Primitive structures which will become gonads and genital tract are identical at this stage. | *Primitive structures which will become gonads and genital tract are identical at this stage. | ||
*Paired mesonephric ducts (Wolffian) or paramesonephric (Mullerian) ducts fuse caudally with urogenital sinus. | *Paired mesonephric ducts (Wolffian) or paramesonephric (Mullerian) ducts fuse caudally with urogenital sinus. | ||
| − | + | (Metanephros - becomes the kidney). | |
===Gonadal differentiation=== | ===Gonadal differentiation=== | ||
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*Absence of testes in presence of ovaries allows paramesonephric ducts to develop under influence of oestrogen to oviduct, uterus, cervix and cranial vagina. | *Absence of testes in presence of ovaries allows paramesonephric ducts to develop under influence of oestrogen to oviduct, uterus, cervix and cranial vagina. | ||
| − | + | ===Summary of determinants of sexual development=== | |
Chromosomal or genetic sex = sex chromosomes | Chromosomal or genetic sex = sex chromosomes | ||
<br>Gonadal sex = ovary or testis | <br>Gonadal sex = ovary or testis | ||
<br>Phenotypic sex = usually determined by gonad | <br>Phenotypic sex = usually determined by gonad | ||
Revision as of 10:45, 22 September 2009
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This article is still under construction. |
EMBRYOLOGICAL DEVELOPMENT OF THE GENITAL TRACT
Early embryo
- Small indifferent gonads.
- Primitive structures which will become gonads and genital tract are identical at this stage.
- Paired mesonephric ducts (Wolffian) or paramesonephric (Mullerian) ducts fuse caudally with urogenital sinus.
(Metanephros - becomes the kidney).
Gonadal differentiation
- Determined by the presence of the SRY gene of the Y chromosome (sex determining region of the Y chromosome) which encodes “testicular determining factor” protein (TDF).
- Lack of SRY gene (i.e. XX females) leads to ovarian differentiation.
Development of phenotypic sex
- The sex of the embryonic gonad normally determines which reproductive duct system develops.
- Testes induce development of mesonephric (Wolffian) duct system in to epididymis and vas deferens and cause regression of paramesonephric (Mullerian) duct by ”mullerian inhibitory substance”, (MIS).
- Absence of testes in presence of ovaries allows paramesonephric ducts to develop under influence of oestrogen to oviduct, uterus, cervix and cranial vagina.
Summary of determinants of sexual development
Chromosomal or genetic sex = sex chromosomes
Gonadal sex = ovary or testis
Phenotypic sex = usually determined by gonad