[Cloning and stem cells. Social, ethical and moral impact].

Stem cells are non-specialised cells, but capable to develop into differenciated (or specialised) cells, that maintain a specific function until they die. Stem cells are obtained from blastocysts. Despite of their therapeutic potential, their origin has generated much controversy and confrontation because of ethical (and moral.) reasons. However, stem cells can also be supplied by adult cells, that are present in the tissue in a quiescient stage, waiting for the appropriate signals to develop into differenciated cells. This type cells is an alternative source for stem cells, and their utilization for medical treatment of degenerative diseases presents no ethical problems.