A cell is the basic unit of composition of the living, which in a first classification is divided into unicellular (single cell) and pluricelulares (more than one cell).

A stem cell that is capable of generating other. The stem cell par excellence is the zygote, resulting from the union of egg and sperm, and is capable of reproducing up to give rise to a whole organism.

Types of stem cells

Although the definition of stem cell involves its ability to generate other, not all stem cells have the same possibilities for differentiation in other cells. According to this capability stem cells are classified into:

·  Totipotentes or totipotenciales: they are able to transform into all the cells of an embryo and the cells outside the embryo, necessary for the development of the same as the placenta.

They are, after all, capable of giving rise to a living being. The zygote is a cell totipotente leading to the formation of other until blastocyst, which will no longer be totipotent cells. Corresponds to the embryonic stage for a living before becoming fetus.

·  Pluripotentes or pluripotenciales: they are able to generate cells from any part of the fabric of an organization, but by themselves would not be able to give rise to a new living being. There in the fetus.

·  Multipotentes or pluripotent: are those found in living things live once and it is believed that only give rise to specialized cells in certain tissues.

Adult Stem Cells

Scientists have demonstrated the existence of pluripotent stem cells in some tissues of adults. In the spinal cord, for example, have identified a number of types such as mesenchymal and hematopoietic cells.

These cells are created so far are pluripotent, but are studying the possibility that adult stem cells can turn into any tissue, ie pluripotencialesSo far it is only known to happen with embryonic.

Aplicaciones Applications

Stem cells are the solution to the conflict that sometimes arises with transplants, as the new organ or tissue would arise from stem cells of the individual.

There are many studies on the potential applications of these stem cells to cure diseases that are characterized by the gradual destruction cell as Alzheimer's.

The understanding of the operation and classes of stem cells is also a way to tackle cancer. This disease is an uncontrolled growth of certain cells that eventually destroy the other.

Legislation in Spain

According to the Law 14/2007, of July 3, and the provisions of earlier reforms, in Spain is authorized the use of stem cells from embryos, but the conditions under which they are available are limited.

The Spanish law expressly prohibits devoted to creating embryos for research. The studies can be made only with embryos dead or unable to develop.

Moreover, in all cases to use embryos mentioned consent is required from the donor. The health authorities are obliged to inform him of the purposes for which they are used by the embryo.

In research with embryos permitted by law can be created or cloned stem cells from them. What can not be cloned an embryo is complete, which allows them to the laws of other countries like the UK.