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How is
Cloning Done?
Genetic copying involves transferring a cell
nucleus from the donor cell (the one to be copied)
into a recipient cell (typically an unfertilized
egg token from an animal soon after ovulation). Cc
(Copycat) was made from an ovarian cell, but the
idea of cloning is that any body could be used.
The vet takes a small skin sample (much like
taking a skin punch biopsy) from the abdomen of a
living cat or one which has just died. This
requires only local anesthesia and a small shaved
area in a living cat. The punched out area is
closed with a couple stitches. This tissue sample
is sent (or taken by courier) to a biotechnology
lab in a special mailing package to preserve it.
At the laboratory, the cells are grown,
harvested and frozen in liquid nitrogen. When
needed, the tissue cells are put in petri dishes
and provided with nutrients so that they divide
and multiply. They may need chemical treatment to
stimulate cell division. Within days, new skin
cells appear and within one month, the new cell
count totals in the millions. This is much like
growing skin for skin grafts and this method could
be used to grow new tissues for transplant.
Nuclei can now be extracted from these cultured
cells of the tissue donor (the biological
"parent"). The extracted nuclei are
inserted into recently ovulated egg cells (ova),
which have had their original nucleus removed in a
process called nuclear transfer. The egg cell
donor may have been chemically stimulated into
producing these eggs. Since cats are induced
ovulators (ovulation is triggered by the act of
mating) they could be made to ovulate by physical
rather than chemical means.
The egg cells which
now contain transplanted nuclei from the tissue
culture are chemically treated to stimulate the
normal division of a fertilized egg cell into an
embryo. This is implanted in the womb of a
surrogate mother cat. If all of the preceding
stages have been successful, the embryo continues
to develop. If the fetus is carried to term, the
surrogate mother will give birth to offspring that
will be genetic matches of the original cat.
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