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In addition there is a chance that sperm
samples get mixed up so that a kitten with 'Stud
Cat X' on its pedigree was in fact fathered by
'Stud Cat Y'. In a breeding program this could
cause havoc as the 'wrong genes' get passed on and
inadvertent and undesirable cross-breeding might
occur. Artificial insemination is not permitted in
breeding programs. Breeders prefer to verify that
the correct genes are passed on by putting the two
cats together to mate physically.
Test tube methods such
as IVF and embryo transfer are potentially useful
is a queen can ovulate, but is unable to carry a
litter to term or if the queen can ovulate but the
sperm cannot reach the eggs. The ova can be
removed and fertilized using test tube methods.
The fertilized eggs could be implanted back into
the queen or into a surrogate mother who has
ovulated but not been impregnated by a stud cat.
Once again there is a possibility of genetic
mix-ups if the surrogate mother has been
impregnated.
Egg donation isn't really an issue in cats,
because it is used for the benefit of infertile
females who want to have babies. An infertile
female cat doesn't benefit a breeding program by
passing on someone else's genes when it is the
infertile cat's genes which are needed.
Parthenogenesis
and Egg Fusion
While much attention is currently turned to
cloning an individual from a body cell, there is
another form of cloning, or at least of producing
an individual from donor cells without
fertilization. Human fertility studies have shown
that an egg cell can be made to divide and develop
without it being fertilized by a sperm. This would
create an individual whose genes all come from a
single parent.
Egg cells contain only half the number of
chromosomes that are found in body cells (because
the other half of the set is contributed by the
sperm cells). The "clone" would not
contain any back-up copies of genes to compensate
for faulty ones. The offspring would be female
(since they only inherit an X gene) and would
contain different combinations of the mother's
genes. They could look quite different e.g.
different eye color/fur color because the mother
may carry traits which are masked by other traits.
They would not be true clones, but they could
possibly produce clones themselves.
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