Institute of Animal Production, Prague 10,
Czech Republic (fulka.josef@vuzv.cz)
Since Dolly the sheep was born in
1996 the success in the production of cloned animals has been reported, after
transfer of somatic cell nucleus into enucleated oocyte, in ten another
mammalian species (mouse, mule, horse, rat, rabbit, cat, cow, goat, pig and
interspecies-specific clone: muflon-sheep). However, the success of mammalian
cloning is extremely low - approximately 3%, some of cloned animals have serious
health and morphological abnormalities and this clearly speaks against the use
of this procedure in humans. Nuclear transfer (cloning) does not exclusively
lead to production of an embryo from which a new individual will be eventually
born (reproductive cloning). More promising is so called „therapeutic cloning“.
Also in this case the embryo is produced. This embryo is not transferred into
the uterus, but it is used for the production of so called „embryonic stem
cells“. It is generally believed that with these cells some presently
untreatable diseases and serious injuries could be treated. However, even in
this case, some problems and still unanswered questions exit.