When a woman undergoes
in-vitro fertilization, she is given medication that causes her to
produce perhaps two dozen mature ova. These are extracted and then
fertilized, usually with sperm provided by her husband, male partner, or
friend. About three days
later, surviving embryos develop to the blastocyst stage. They consist
of a collection of 4 to 10
This photograph shows a seven-cell embryo
held between two micro-pipettes. In this case, portions of six cells
can be seen; the seventh is out of view behind the remaining cells. Two
to five days after fertilization, one or more of the healthiest embryos are
selected and implanted in the woman's womb, in the hope that one
or two will develop into a single newborn or twins. The rest are quickly
deep frozen in liquid nitrogen for potential future use.
These are sometimes called "pre-embryos." They have no brain, central
nervous system, eyes, heart, lungs, or other internal organs. They
have no organs to see, hear, touch, taste; they lack a body, head, arms,
legs; they have no self awareness, memory, thought processes, or
consciousness. They are smaller than a pin-prick. They consist of a number
of identical, undifferentiated cells that contain human DNA. They do have
a chance to grow into fetuses and become newborn babies if they are
implanted into a uterus.
believe that the pre-embryos are human persons with souls. Many skeptics argue that souls
do not exist -- in either embryos or adult people.
Handling the surplus embryos:
There is no method to dispose of the excess embryos that is morally
acceptable to everyone. Occasionally,
an infertile couple will need to go back for a second try at achieving a pregnancy.
This happens when the first procedure did not produce a pregnancy, or
when the couple wants to have an additional child. One or more additional embryos are
then removed from storage, thawed out, and
implanted. But even when that happens, perhaps 16 of the couple's embryos will
still remain frozen. These surplus embryos will almost inevitably be destroyed:
Perhaps 50% do not survive the freezing or thawing process.
Others will die during storage.
Equipment malfunction, perhaps after decades of storage, might destroy
hundreds of embryos.
Some parents ask that the surplus embryos be destroyed in order to save
the cost of maintaining them in storage.
Some clinics simply dispose of surplus embryos without freezing them.
Finding a use for surplus embryos is not simple:
Most couples are fertile and can have children on their own. They have no need
couples also normally have no use for other couples' surplus embryos. They can have the clinic implant a
new embryo which they form in the lab:
woman's ovum and/or her partners sperm, if this is possible.
From the man's sperm and ova from another woman.
Most infertile women and couples find these to be preferred routes, because the
resultant child will genetically be partly their/her own.
Sometimes women wishing to become pregnant are artificially inseminated. Again, this does
not involve a surplus embryo.
A very few surplus embryos are donated to research. Their stem cells
are removed. The embryos die in the process.
A new option has been developed, and is being actively promoted by
some religious conservatives: embryo adoption.