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| − | ===EMBRYOLOGICAL DEVELOPMENT OF THE GENITAL TRACT=== | + | ===Anomalies of Development=== |
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| − | ====Early embryo====
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| − | Small indifferent gonads. The primitive structures which will become gonads and genital tract are identical at this stage.
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| − | Paired mesonephric ducts (Wolffian) or paramesonephric (Mullerian) ducts fuse caudally with urogenital sinus.
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| − | <br>(Metanephros - becomes the kidney).
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| − | ====Gonadal differentiation====
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| − | This is 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).
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| − | <br>Lack of SRY gene (i.e. XX females) leads to ovarian differentiation.
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| − | ====Development of phenotypic sex====
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| − | The sex of the embryonic gonad normally determines which reproductive duct system develops.
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| − | <br>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).
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| − | <br>Absence of testes in presence of ovaries allows paramesonephric ducts to develop under influence of oestrogen to oviduct, uterus, cervix and cranial vagina.
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| − | '''Summary of determinants of sexual development'''
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| − | <br>Chromosomal or genetic sex = sex chromosomes
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| − | <br>Gonadal sex = ovary or testis
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| − | <br>Phenotypic sex = usually determined by gonad
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| − | <br> Back to [[Reproductive - Pathology]]
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| − | <Br>Information by permission of Professor RW Else
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