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Title: Congenitale afwijkingen van de genitale tractus: embryologische en genetische achtergrond
Author(s): HOSTE G, GRAUWEN N, VERGUTS J, DEVRIENDT K
Journal: Tijdschrift voor Geneeskunde
Volume: 70    Issue: 4   Date: 2014   
Pages: 206-210
DOI: 10.2143/TVG.70.04.2001559

Abstract :
In het embryonale stadium is er een gemeenschappelijke oorsprong van de urogenitale tractus. De genetische aanleg van het embryo stuurt de geslachtelijke differentiatie. Tijdens de verdere ontwikkeling treedt er onder invloed van het TDF-gen (“testis determining factor”) (gelegen in de “sex determining region” op het Y-chromosoom) een differentiatie op van de gonaden. Na acht weken evolueren de externe genitaliën in mannelijke of vrouwelijke richting door de aan- of de afwezigheid van (dihydro)testosteron.
Stoornissen in dit ontwikkelingsproces, zowel op embryologisch als genetisch vlak, geven aanleiding tot congenitale afwijkingen van de genitale tractus.






Female genital tract congenital malformations: embryologic and genetic aspects
Embryologically and anatomically, the reproductive and the urinary system share common origins. This manuscript provides an overview of the embryology of the female and the male genital tract.
The genotype and the chromosomal sex of a foetus is determined at the conception by the presence of either the XX or the XY genotype. Until the beginning of the seventh week, the development of the genital system appears morphologically identical in male and female embryos. In both sexes, germ cells and sex cords are present in the cortical and medullary regions of the undifferentiated gonad, the mesonephric and the paramesonephric ducts lying side by side.
Under the influence of the TDF gene (“testis determining factor”) located on the short arm of the Y chromosome, the sex cords of male embryos start to produce TDF, causing a differentiation of the cells in the medullary region of the primitive sex chords.
TDF induces the testis to develop and to produce anti-Mullerian hormone (AMH). AMH causes the Leydig cells of the testis to secrete androgens; it also induces the degeneration of the paramesonephric ducts. The external genital organs differentiate in male direction due to the presence of androgens. In female embryos TDF is not present, which results in the regression of the mesonephric duct and the growth of the paramesonephric ducts.
A disordered differentiation during the embryogenesis can result in congenital abnormalities, affecting the female reproductive tracts, the renal tract and the lower intestines.


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