Difference between revisions of "Hypothalamus Differences in the Male and Female - Anatomy & Physiology"
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| + | {{toplink | ||
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| + | |linkpage =Reproductive System - Anatomy & Physiology | ||
| + | |linktext =Reproductive System | ||
| + | |maplink = Reproductive System (Content Map) - Anatomy & Physiology | ||
| + | |pagetype =Anatomy | ||
| + | |sublink1=Reproductive System - Anatomy & Physiology#Puberty | ||
| + | |subtext1=PUBERTY | ||
| + | }} | ||
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== Introduction == | == Introduction == | ||
| − | The | + | * The hypothalamus is inherently female. |
| + | * Testosterone 'defeminizes' the brain during embryogenesis and eliminates the GnRH surge centre in males. | ||
| + | * The female foetus has no testes to produce testosterone, thus developes a hypothalamic GnRH surge centre. | ||
== Defeminizing the Hypothalamus in the Male == | == Defeminizing the Hypothalamus in the Male == | ||
| − | Testosterone crosses the | + | * Testosterone crosses the blood-brain barrier and is converted into oestradiol. |
| + | * In the brain, oestradiol 'defeminizes' the hypothalamus. | ||
| + | * Surge centre function is minimized. | ||
| + | * Complete 'defeminization' of the brain requires postnatal exposure to androgens. | ||
| + | * Continued exposure to androgens is required to render the surge centre inoperative. | ||
| + | |||
== The Female Hypothalamus == | == The Female Hypothalamus == | ||
| − | Foetal ovaries produce oestradiol, but this does NOT defeminize the | + | * Foetal ovaries produce oestradiol, but this does NOT defeminize the hypothalamus. |
| − | + | * A protein called alpha-fetoprotein binds oestradiol to prevent it from crossing the blood brain barrier, therefore oestradiol cannot effect the hypothalamus. | |
| − | Alpha fetoprotein functions as | + | * Alpha-fetoprotein is synthesized firstly by the embryonic yolk sac and then by the foetal liver. |
| − | + | * Alpha fetoprotein functions as: | |
| − | + | ** Foetal blood osmotic regulator | |
| − | + | ** Carrier of fatty acids | |
| − | |||
| − | |||
| − | |||
Revision as of 13:38, 4 September 2008
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Introduction
- The hypothalamus is inherently female.
- Testosterone 'defeminizes' the brain during embryogenesis and eliminates the GnRH surge centre in males.
- The female foetus has no testes to produce testosterone, thus developes a hypothalamic GnRH surge centre.
Defeminizing the Hypothalamus in the Male
- Testosterone crosses the blood-brain barrier and is converted into oestradiol.
- In the brain, oestradiol 'defeminizes' the hypothalamus.
- Surge centre function is minimized.
- Complete 'defeminization' of the brain requires postnatal exposure to androgens.
- Continued exposure to androgens is required to render the surge centre inoperative.
The Female Hypothalamus
- Foetal ovaries produce oestradiol, but this does NOT defeminize the hypothalamus.
- A protein called alpha-fetoprotein binds oestradiol to prevent it from crossing the blood brain barrier, therefore oestradiol cannot effect the hypothalamus.
- Alpha-fetoprotein is synthesized firstly by the embryonic yolk sac and then by the foetal liver.
- Alpha fetoprotein functions as:
- Foetal blood osmotic regulator
- Carrier of fatty acids