Since the 1970s, embryologists and human geneticists have placed great importance on and have applied much of their research funding to understanding developmental processes, for example, how a fertilized egg becomes a biologically complex human being. They examine the chains of genetic events that lead to the development of distinct tissues and organs in the growing organism. The thinking is that genes may determine which of two alternative paths of development is followed. To rationalize this research scientists argue that the knowledge gained from genetic research on the human embryo will lead to a more comprehensive assault against genetically caused diseases. The technological advances that have allowed this research are in vitro fertilization (IVF) and genetic engineering. The former provides scientists access to embryos outside the woman's body and under laboratory conditions; the latter provides the research tools for studying the genes and related processes.
In November 1986, about thirty scientists and clinicians met at the CIBA Foundation (now known as the Novartis Foundation) in London to discuss whether it was possible to diagnose genetic conditions in two-day- old human embryos. They decided that it was, due to IVF procedures already established in advanced infertility practices. Meanwhile, researchers in the bioengineering industry and academia were perfecting techniques to detect specific genes or enzymes (the chemicals genes make) in embryo cells. They found that they could remove a single cell