FREEMARTINS
- AGRICULTURE
News: Freemartins: black sheep among the
cattle
What's
in the news?
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In agricultural settings, because
freemartins can’t reproduce, farmers often identify them through physical or
behavioural traits.
Freemartins:
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A freemartin is infertile female
cattle with masculinized behaviour and
non-functioning ovaries.
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Phenotypically, the animal appears female,
but various aspects of female reproductive development are altered due
to acquisition of anti-Müllerian hormone from the male twin.
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Genetically, the animal is chimeric
- Karyotype of a sample of cells shows XX/XY chromosomes.
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The animal originates as a female (XX),
but acquires the male (XY) component in utero by exchange of some cellular
material from a male twin, via vascular connections between placentas - an
example of micro chimerism.
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The chimerism is mainly present in
the hematopoietic stem cells.
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Freemartins
behave and grow in a similar way to castrated male cattle (steers).