Human embryology and fertilisation bill

This week has seen debates over whether Labour MPs should be entitled to a free vote, allowing them to vote against parts of the human embryology and fertilisation bill. The bill is designed to bring the 1990 regulatory framework for fertility treatment and embryo research in line with scientific advances.

This is a controversial area with strong views and beliefs from both sides of the argument. It is important that information on this subject is clearly presented. 

A contentious element of the bill is whether to allow the creation of hybrid animal-human embryos for use in medical research into treatments for diseases such as Parkinson's and Alzheimer's.  

To create these hybrids, the nucleus of the animal egg would be removed and then replaced with the nucleus of a human cell such as a skin cell. Animal eggs would primarily be used as a way of addressing the scarcity of human eggs available for research. 

The resulting hybrid embryo can be grown in the lab for a few days and harvested for stem cells. Stem cells are 'master' cells, which can develop into many different cell types. At the stage where stem cells are extracted the embryo is still just a microscopic cluster. 

If the original human cell nucleus that is inserted is from a donor with a disease such as Parkinson's, then the stem cells will also contain the same genetic defects. The stem cells can develop into different types of tissues and this allows scientists to study the disease processes. 

It also means that one day some stem cells may have the potential to be transplanted into patients as a cure for some diseases.