A human embryo can split into twins or triplets until about 14 days after fertilization

Egg and sperm: some people believe an embryo must be fully protected from conception onwards (Wellcome Images/Spike Walker)

Human blastocyst on the tip of a pin: embryonic stem cells can be grown from cells found in the blastocyst (Wellcome Images/Yorgos Nikas)

Some people think an embryo deserves special protection from about 14 days after fertilization

Many patients could one day benefit from embryonic stem cell research

The rules controlling embryonic stem cell research vary around the world and have been the topic of much discussion

Embryonic stem cell research poses a moral dilemma. It forces us to choose between two moral principles:

In the case of embryonic stem cell research, it is impossible to respect both moral principles.To obtain embryonic stem cells, the early embryo has to be destroyed. This means destroying a potential human life. But embryonic stem cell research could lead to the discovery of new medical treatments that would alleviate the suffering of many people. So which moral principle should have the upper hand in this situation? The answer hinges on how we view the embryo. Does it have the status of a person?

Chapter 1 of this film introduces some of the key ethical arguments. Watch this film and others on our films page.

The moral status of the embryo is a controversial and complex issue. The main viewpoints are outlined below.

1. The embryo has full moral status from fertilization onwards Either the embryo is viewed as a person whilst it is still an embryo, or it is seen as a potential person. The criteria for personhood are notoriously unclear; different people define what makes a person in different ways.

Development from a fertilized egg into to baby is a continuous process and any attempt to pinpoint when personhood begins is arbitrary. A human embryo is a human being in the embryonic stage, just as an infant is a human being in the infant stage. Although an embryo does not currently have the characteristics of a person, it will become a person and should be given the respect and dignity of a person.

An early embryo that has not yet been implanted into the uterus does not have the psychological, emotional or physical properties that we associate with being a person. It therefore does not have any interests to be protected and we can use it for the benefit of patients (who ARE persons).

The embryo cannot develop into a child without being transferred to a womans uterus. It needs external help to develop. Even then, the probability that embryos used for in vitro fertilization will develop into full-term successful births is low. Something that could potentially become a person should not be treated as if it actually were a person. A candidate for president is a potential president, but he or she does not have the rights of a president and should not be treated as a president.

2. There is a cut-off point at 14 days after fertilization Some people argue that a human embryo deserves special protection from around day 14 after fertilization because:

3. The embryo has increasing status as it develops An embryo deserves some protection from the moment the sperm fertilizes the egg, and its moral status increases as it becomes more human-like.

There are several stages of development that could be given increasing moral status:

1. Implantation of the embryo into the uterus wall around six days after fertilization. 2. Appearance of the primitive streak the beginnings of the nervous system at around 14 days. 3. The phase when the baby could survive if born prematurely. 4. Birth.

If a life is lost, we tend to feel differently about it depending on the stage of the lost life. A fertilized egg before implantation in the uterus could be granted a lesser degree of respect than a human fetus or a born baby.

More than half of all fertilized eggs are lost due to natural causes. If the natural process involves such loss, then using some embryos in stem cell research should not worry us either.

We protect a persons life and interests not because they are valuable from the point of view of the universe, but because they are important to the person concerned. Whatever moral status the human embryo has for us, the life that it lives has a value to the embryo itself.

If we judge the moral status of the embryo from its age, then we are making arbitrary decisions about who is human. For example, even if we say formation of the nervous system marks the start of personhood, we still would not say a patient who has lost nerve cells in a stroke has become less human. (But there is a difference between losing some nerve cells and losing the complete nervous system - or never having had a nervous system).

If we are not sure whether a fertilized egg should be considered a human being, then we should not destroy it. A hunter does not shoot if he is not sure whether his target is a deer or a man.

4. The embryo has no moral status at all An embryo is organic material with a status no different from other body parts.

Fertilized human eggs are just parts of other peoples bodies until they have developed enough to survive independently. The only respect due to blastocysts is the respect that should be shown to other peoples property. If we destroy a blastocyst before implantation into the uterus we do not harm it because it has no beliefs, desires, expectations, aims or purposes to be harmed.

By taking embryonic stem cells out of an early embryo, we prevent the embryo from developing in its normal way. This means it is prevented from becoming what it was programmed to become a human being.

Different religions view the status of the early human embryo in different ways. For example, the Roman Catholic, Orthodox and conservative Protestant Churches believe the embryo has the status of a human from conception and no embryo research should be permitted. Judaism and Islam emphasize the importance of helping others and argue that the embryo does not have full human status before 40 days, so both these religions permit some research on embryos. Other religions take other positions. You can read more about this by downloading the extended version of this factsheet below.

Extended factsheet with a fuller discussion of the issues by Kristina Hug (pdf) EuroStemCell film "Conversations: ethics, science, stem cells" EuroStemCell factsheet on ethical issues relating to the sources of embyronic stem cells EuroStemCell factsheet on the science of embryonic stem cells EuroStemCell FAQ on human embryonic stem cells and their use in research EuroStemCell summaries of regulations on stem cell research in Europe Booklet for 16+ year olds about stem cells and ethics from the BBSRC Research paper on the ethics of embryonic stem cell research by Kristina Hug

This factsheet was created by Kristina Hug and reviewed by Gran Hermern.

Images courtesy of Wellcome Images: Egg and sperm by Spike Walker; Blastocyst on pin by Yorgos Nikas; Diabetes patient injecting insulin by the Wellcome library, London.

Other images from "Conversations : ethics, science, stem cells", a film by EuroStemCell.

Read this article:
Embryonic Stem Cell Research - An Ethical Dilemma