Changes

==Introduction==

==Introduction==

Development of the reproductive system is a complex process relying on numerous systems and conditions to ensure appropriate structures are formed and the rate of development is maintained within the embryo. There are several important criteria that determine appropriate reproductive system development; '''genetic sex''' which determines the sex of the embryo, '''gonadal sex''' and '''phenotypic sex''' which both determine sexual differentiation. Genetic sex determines gonadal sex which in turn determines phenotypic sex. Sex determination relates to the genetic or environmental process which determines the sex of an individual whilst sexual differentiation represents the development of internal and external genitalia.

Development of the reproductive system is a complex process relying on numerous systems and conditions to ensure appropriate structures are formed and the rate of development is maintained within the embryo. There are several important criteria that determine appropriate reproductive system development; '''genetic sex''' which determines the sex of the embryo, '''gonadal sex''' and '''phenotypic sex''' which both determine sexual differentiation. Genetic sex determines gonadal sex which in turn determines phenotypic sex. Sex determination relates to the genetic or environmental process which determines the sex of an individual whilst sexual differentiation represents the development of internal and external genitalia.

There are a number of genes involved in this stage of bipotential gonadal determination; '''WT-1''', '''SF-1''', '''Lim-1''' and '''EMx-2'''. The development of either the Wolfian ducts is caused by the genes '''SRY''', '''SOX-9''', '''DMRT''' and '''1/2'''. The Mullerian ducts develop as a result of the genes '''DAX-1''' and '''Wnt-4'''.

There are a number of genes involved in this stage of bipotential gonadal determination; '''WT-1''', '''SF-1''', '''Lim-1''' and '''EMx-2'''. The development of either the Wolfian ducts is caused by the genes '''SRY''', '''SOX-9''', '''DMRT''' and '''1/2'''. The Mullerian ducts develop as a result of the genes '''DAX-1''' and '''Wnt-4'''.

===Pimary Sexual Differentiation Phase===

===Primary Sexual Differentiation Phase===

This phase represents the initial phase of differentiation of reproductive tissues. The male Y chromosome in mammals contains genetic code that results in the production of '''testes-determining factor (TDF)''' which is responsible for causing the gonads to develop into testes. In the female fetus, TDF is not produced as there is no Y chromosome and therefore the gonads develop into ovaries. As the testes begin to develop under the influence of TDF, the '''Sertoli cells''' within the testes begin to produce '''Anti-Mullerian hormone (AMH)''' and this has two main effects. It causes the '''Leydig cells''' within the testes to develop which are able to produce testosterone and this testosterone begins the development of the male duct system. Under the influence of AMH these Laydig cells also begin to produce '''dihydrotestosterone''' which, per the above explanation, is also a key signalling molecule in reproductive system development resulting in the development of the penis, scrotum and accessory sex glands. The second key effect of AMH is the regression of the paramesonephric duct system. In females, the lack of TDF and AMH allows the paramesonephric ducts to become the oviducts, uterus, cervix and internal parts of the vagina.

This phase represents the initial phase of differentiation of reproductive tissues. The male Y chromosome in mammals contains genetic code that results in the production of '''testes-determining factor (TDF)''' which is responsible for causing the gonads to develop into testes. In the female fetus, TDF is not produced as there is no Y chromosome and therefore the gonads develop into ovaries. As the testes begin to develop under the influence of TDF, the '''Sertoli cells''' within the testes begin to produce '''Anti-Mullerian hormone (AMH)''' and this has two main effects. It causes the '''Leydig cells''' within the testes to develop which are able to produce testosterone and this testosterone begins the development of the male duct system. Under the influence of AMH these Leydig cells also begin to produce '''dihydrotestosterone''' which, per the above explanation, is also a key signalling molecule in reproductive system development resulting in the development of the penis, scrotum and accessory sex glands. The second key effect of AMH is the regression of the paramesonephric duct system. In females, the lack of TDF and AMH allows the paramesonephric ducts to become the oviducts, uterus, cervix and internal parts of the vagina.

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[[Category:To Do - Review]]

[[Category:To Do - Review]]

[[Category:Developmental Biology]] [[Category:Reproductive System - Anatomy & Physiology]]

[[Category:Developmental Biology]] [[Category:Reproductive System - Anatomy & Physiology]]