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| − | = Internal Genetalia =
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| − | * Male: '''Wolffian Duct''' developes from the '''Mesonephric Duct'''
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| − | * Female: '''Mullarian Ducts''' develop from the '''Paramesonephric Duct'''
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| − | * This is dependent on appropriate hormonal influence.
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| − | == Male ==
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| − | * '''MIH''' from '''Sertoli cells''' and '''Androgens''' from '''Leydig cells''' prevent spontaneous development of female internal genetalia.
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| − | * '''Androgens''' actively maintain '''Wolffian Ducts''', which give rise to male internal genetalia:
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| − | ** Epididymis
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| − | ** Vas Deferens
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| − | ** Vesicular Glands/ Seminal Vesicles
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| − | * '''MIH''' causes Mullarian Ducts to regress
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| − | == Female ==
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| − | * Wolffian Ducts spontaneously regress in absence of Androgens.
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| − | * '''Mullarian Ducts''' persist to give rise to female internal genetalia:
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| − | ** Oviducts
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| − | ** Uterus
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| − | ** Cervix
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| − | ** Cranial Vagina
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| − | * Normal Ovarian activity is NOT essential for the development of normal female internal genetalia.
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| − | ----
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| − | = External Genetalia =
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| − | == Male ==
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| − | * Potential to develop male of female external genetalia. '''Testosterone''' is required to develop male external genetalia.
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| − | * Androgen secretion from the Testes induces:
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| − | ** '''Urethral folds''' to fuse to allow enclosure of the urethral tube. This, together with the cells from the '''genital swelling''', forms the '''shaft of the Penis'''.
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| − | ** '''Genital swellings''' fuse in the midline to allow formation of the '''Scrotum'''
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| − | ** '''Genital Tubercle''' expands to give rise to the '''Glans Penis'''
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| − | == Female ==
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| − | * Development is ensured by the absence of Testosterone, it is independent of Ovarian endocrine activity.
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| − | * '''Urethral folds''' and '''Genital Swellings''' remain separate to form the '''Labia Minora and Majora'''.
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| − | * '''Genital tubercle''' forms the '''Clitoris'''
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| − | * Exposure of the female tract to Androgens will masculinise external genetalia.
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| − | * Failure of proper endocrine communication between the gonads, internal and external genitalia can lead to '''dissociation''' of gonadal and genital sex.
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| − | ----
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| − | = Sexual Differentiation of the Brain =
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| − | == Male ==
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| − | * '''Testosterone''' secreted into the blood reaches the brain.
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| − | * Converted to Dehydrotestosterone and '''Oestradiol''' by Aromatase enzymes in the Hypothalamus.
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| − | * Oestradiol masculinises the brain
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| − | == Female ==
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| − | * '''Alpha Fetoprotein''' binds Oestradiol, preventing it from crossing the blood-brain barrier.
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| − | * Oestradiol cannot access the Hypothalamus
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| − | * Protects female brain from masculising effects of Oestradiol.
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| − | ----
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| − | = Associated Disorders =
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| − | * [[Fertilisation, Implantation and Early Embryonic Development -Turner's Syndrome - Anatomy & Physiology|Turner's Syndrome]]
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| − | * [[Fertilisation, Implantation and Early Embryonic Development -Kleinfelter's Syndrome - Anatomy & Physiology|Kleinfelter's Syndrome]]
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| − | * [[Fertilisation, Implantation and Early Embryonic Development -Testicular Feminisation - Anatomy & Physiology|Testicular Feminisation]]
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| − | * [[Fertilisation, Implantation and Early Embryonic Development -Adrenogenital Syndrome - Anatomy & Physiology|Adrenogenital Syndrome]]
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| − | * [[Fertilisation, Implantation and Early Embryonic Development -Intersex - Anatomy & Physiology|Intersex]]
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| − | * [[Fertilisation, Implantation and Early Embryonic Development -Bovine Freemartinism - Anatomy & Physiology|Bovine Freemartinism]]
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