Difference between revisions of "Bovine Freemartinism"
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| + | <big><center>[[Reproductive System|'''BACK TO REPRODUCTIVE SYSTEM''']]</center></big> | ||
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| + | <big><center>[[Reproductive_System#Fertilisation.2C_Implantation_and_Early_Embryonic_Development|'''BACK TO FERTILISATION , IMPLANTATION and EARLY EMBRYONIC DEVELOPMENT''']]</center></big> | ||
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| + | <big><center>[[Fertilisation%2C_Implantation_and_Early_Embryonic_Development_-Sexual_Differentiation-_Anatomy_%26_Physiology#Associated_Disorders|'''BACK TO SEXUAL DIFFERENTIATION''']]</center></big> | ||
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== Aetiology == | == Aetiology == | ||
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* Mesonephric (Wolffian) ducts persist in the female twin and may form rudimentary male tubular genitalia. | * Mesonephric (Wolffian) ducts persist in the female twin and may form rudimentary male tubular genitalia. | ||
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== Diagnosis == | == Diagnosis == | ||
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* Clinical genital abnormalities | * Clinical genital abnormalities | ||
* Presence of sex chromatin bodies in circulating leukocytes of the male co-twin | * Presence of sex chromatin bodies in circulating leukocytes of the male co-twin | ||
| − | * Chimerism (XX/XY) of [[ | + | * Chimerism (XX/XY) of [[Haematopoiesis_-_Anatomy_%26_Physiology|haematopoeitic cells]]. Blood tests can be used to demonstrate different chromosome complement in nucleated leukocytes and presence of two blood groups in each twin. |
* Rectal palpation and vaginoscopy reveal a shortened vagina | * Rectal palpation and vaginoscopy reveal a shortened vagina | ||
| − | ** In calves 1-4 weeks old, the vagina is normally 13-15cm in length compared to 5-6cm in a freemartin. | + | ** In calves 1-4 weeks old, the [[/Female_Reproductive_Tract_-The_Vagina/Vestibule_-_Anatomy_%26_Physiology|vagina]] is normally 13-15cm in length compared to 5-6cm in a freemartin. |
| − | * Vulva and vestibule patent but vestibule or vagina is blind-ended - can be checked using speculum or probe. | + | * Vulva and vestibule patent but [[/Female_Reproductive_Tract_-The_Vagina/Vestibule_-_Anatomy_%26_Physiology|vestibule or vagina]] is blind-ended - can be checked using speculum or probe. |
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== Morphology == | == Morphology == | ||
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* Enlarged clitoris, long tufts of hair round vulva, skin fold from groin to umbilicus. | * Enlarged clitoris, long tufts of hair round vulva, skin fold from groin to umbilicus. | ||
* Vagina never communicates with uterus | * Vagina never communicates with uterus | ||
| − | * | + | * fibrous cords or non-patent uterine tubes. |
* Ovaries are usually small, cord-like thickenings in the ovarian ligament are semniferous tubules. | * Ovaries are usually small, cord-like thickenings in the ovarian ligament are semniferous tubules. | ||
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Revision as of 09:47, 30 July 2008
Aetiology
- Results from sexual modification of a female twin by the in-utero exchange of blood from a male foetus.
- Freemartin is XX genetic female, but becomes an XX/XY chimera.
- 90% of female calves born co-twin to a male will be freemartins.
- There are two theories to explain this:
- Hormonal Theory
- Hormones from the male twin reach the female through vascular anastamoses between the fused placentae to cause masculinisation of the female gonad.
- Cellular theory
- Exhange of blood-forming cells and germ cells between foetuses.
- Reciprocal exchange results in identical erythrocyte antigen types and sex chromosome chimerism (60 XX/XY).
- Hormonal Theory
- Paramesonephric (Mullerian) ducts do not form or atrophy.
- Mesonephric (Wolffian) ducts persist in the female twin and may form rudimentary male tubular genitalia.
Diagnosis
- Clinical genital abnormalities
- Presence of sex chromatin bodies in circulating leukocytes of the male co-twin
- Chimerism (XX/XY) of haematopoeitic cells. Blood tests can be used to demonstrate different chromosome complement in nucleated leukocytes and presence of two blood groups in each twin.
- Rectal palpation and vaginoscopy reveal a shortened vagina
- In calves 1-4 weeks old, the vagina is normally 13-15cm in length compared to 5-6cm in a freemartin.
- Vulva and vestibule patent but vestibule or vagina is blind-ended - can be checked using speculum or probe.
Morphology
- Gonads range from modified Ovaries to structures resembling Testes which are intra-abdominal and do not descend through the inguinal canal (Cryptorchid).
- No spermatogenesis, sterile.
- Produce Testosterone as the major hormone.
- Rudimentary Uterus and Small Vagina.
- Enlarged clitoris, long tufts of hair round vulva, skin fold from groin to umbilicus.
- Vagina never communicates with uterus
- fibrous cords or non-patent uterine tubes.
- Ovaries are usually small, cord-like thickenings in the ovarian ligament are semniferous tubules.