The use of the term "advanced" in the title of this book is somewhat ar bitrary and very much relative with respect to time. Many techniques which were considered at the "cutting edge" of ultrastructural methodology just a few years ago are now rou tin ely used in numerous laboratories. One could cite freeze-fracture, cryothin sectioning, or indeed most of the field of scan ning electron microscopy as concrete examples. Thus the use of the term "ad vanced techniques" must be interpreted with regard to the present state of the art, and is useful only in informing the potential reader that this volume is not a primer to be used as an initial introduction into basic biological elec tron microscopy. Many excellent volumes have filled that niche in the past few years, and it is not intended that this modest book be a complete com pendium of the field. Furthermore, any limited selection of papers on advanc ed techniques necessarily reflects the preferences and arbitrary whims of the editor, thereby excluding many equally important procedures which the knowledgeable reader will readily identify. The first volume of this series appeared approximately five years ago and illustrated techniques which were thought to represent advanced and yet ba sically morphological methods for gaining increased ultrastructural informa tion from biological specimens. The present volume, on the other hand, stresses techniques which provide specific physicochemical data on the speci mens in addition to the structural information."

The past decade has seen a remarkable increase in the use of electron microscopy as a researm tool in biology and medicine. Thus, most institu tions of higher learning now boast several electron optical laboratories having various levels of sophistication. Training in the routine use of elec tron optical equipment and interpretation of results is no longer restricted to a few prestigious centers. On the other hand, temniques utilized by researm workers in the ultrastructural domain have become extremely diverse and complex. Although a large number of quite excellent volumes of electron microscopic temnique are now dedicated to the basic elements available whim allow the novice to acquire a reasonable introduction to the field, relatively few books have been devoted to a discussion of more ad vanced temnical aspects of the art. It was with this view that the present volume was conceived as a handy reference for workers already having some background in the field, as an information source for those wishing to shift efforts into more promising temniques, or for use as an advanced course or seminar guide. Subject matter has been mosen particularly on the basis of pertinence to present researm activities in biological electron microscopy and emphasis has been given those areas whim seem destined to greatly expand in useful ness in the near future."

This volume is a continuation of two prior books on advanced electron microscope techniques. The purpose of this series has been to provide in depth analyses of methods which are considered to be at the leading edge of electron microscopic research procedures with applications in the biological sciences. The mission of the present volume remains that of a source book for the research practitioner or advanced student, especially one already well versed in basic electron optical methods. It is not meant to provide in troductory material, nor can this modest volume hope to cover the entire spectrum of advanced technology now available in electron microscopy. In the past decade, computers have found their way into many research laboratories thanks to the enormous increase in computing power and stor age available at a modest cost. The ultrastructural area has also benefited from this expansion in a number of ways which will be illustrated in this volume. Half of the contributions discuss technologies that either directly or indirectly make extensive use of computer methods."