[Ethical problems raised by new reproductive biotechnologies and stem cells].

Research about the hormonal mechanisms controlling reproduction in mammals has soared during the first half of the 20th century. It has produced a series of discoveries with important outcomes, not only scientific, but also impacting the ways of life. Besides the advent of the contraceptive pill, it has permitted to isolate and cultivate in vitro the female gamete, to fertilize it, thus obtaining a zygote that continues to develop until the blastocyst stage outside the maternal organism. The embryo, transferred into a foster-mother, develops normally until term: the first "test-tube baby" was born in this way in 1978. But the only fact of being able to cultivate the human egg in vitro was to open other possibilities and allow further biological advances: embryonic stem cells (ES cells) obtained from blastocysts and, more recently, from induced Pluripotent Stem cells (iPS), which can potentially be derived from all types of differentiated cell types obtained from adult individuals. From then on, the advent of a new medicine could be anticipated, regenerative because able to replace deficient or absent cells within the organism. As each of these steps was reached, scientists have encountered vigorous opposition from the people: the new potentials disturbed the conceptions that man had of his relationship to nature, in particular in two sensitive domains: sexuality and reproduction. The progress of science has however been accepted by most as soon as it was understood that humanity could anticipate advantages from these advances.