[Structure and functions of the macroglia in the central nervous system. Response to degenerative disorders]

Glial cells have been known for a long time. For many years they have been considered to be merely a support for the structure of nervous tissue. Our limited knowledge of these cells has been mainly due to different methodological problems which made it impossible to discover more about their origin and physiology. Now, however, thanks to the development of immunocytochemical techniques, it has been possible to determine their structure, and their function have been discovered thanks to the modern molecular biology techniques. Thus the importance of the glia in the nervous system, both in normal and in pathological conditions, is now realized. In recent years increasing interest has been shown in the functional role played by macroglia (astrocytes and oligodendrocytes).

Although astrocytes and oligodendrocytes have been classified into different types, according to their morphology, these cells are functionally very heterogeneous depending on the microenvironment in which they are found. However, this is only a measure of the number of key processes in which they participate to the correct functionality of central nervous system.

The diversity of processes in which astrocytes and oligodendrocytes are involved shows that these cells can respond in different ways to neurodegenerative situations, both normal and pathological, in order to maintain the structural integrity of cerebral tissue. Although the role played by oligodendrocytes is less well-known than that played by astrocytes, both cell types may be perfect targets for treatment of nervous system diseases, and also of the neurodegenerative changes due to ageing.