This volume contains papers presented at the Fourth International Altschul Sympo- sium, held June 27-29, 1996, at the University of Saskatchewan in Saskatoon, Saskatche- wan, Canada. The Altschul Symposia Series are held in memory of Rudolf Altschul, a graduate of the University of Prague and a pioneer in the fields of vascular and nervous system biology. Dr. Altschul was head of the Department of Anatomy at the University of Saskatchewan from 1955 to 1963. The Altschul Symposia are made possible by an endow- ment left by Anni Altschul, Dr. Altschul's wife, and by other contributions given by the sponsors listed at the end of this Preface. The objective of the Fourth Altschul Symposium, entitled Cell Biologv and Pathol- ogv of Myelin: Evolving Biological Concepts and Therapeutic Approaches, was to facili- tate the transfer of ideas on the biology and pathology of myelin from the research laboratory to the clinic by providing a forum for discussing the evolving biological con- cepts regarding myelin function in health and disease.

The last decades have witnessed a radical change in our views on central nervous system damage and repair. This change is not only due to the emergence of new powerful tools for the analysis of the brain and its reactions to insults, but it also reflects a conceptual change in the way we approach these problems. As an illustration to this development, it is instructive to go back to the proceedings of a meeting at the NIH in 1955 edited by William F. Windle, which summarizes the disillusioned and pessimistic view on CNS regeneration prevailing at the time. While this generation of researchers were well aware of the issues at stake, they felt they had reached the end of the road; the approaches they had pursued had got stuck and the tools available could not take them any further. I can very well imagine that the participants, most of them leaders in the field, left that conference feeling they had heard their field being sentenced to death.