In recent years, the techniques of electron microscopy have developed so widely and rapidly that they now cover the fields of research once the unique ll:panage of sister research techniques such as biochemistry, physiology, immunology, X-ray diffraction, etc. It is now possible to reach molecular and submolecular levels, making this technique indispensable in every type of research. Electron microscopy alone often provides enough information to solve given problems. In the field of the connective tissue matrix, knowledge of the molecular structure of collagen, pro teoglycans and elastin and their interaction has been to a large extent elucidated by electron microscopy. The field over which electron microscopy ranges in the investigation of the connective tissue matrix is so wide that the aim of this volume is to collect the main ultrastructural acquisitions disseminated in various journals and monographs in one book. The intent ofthis volume is to: (a) integrate different and new microscopic methods and review the results of such an integrative approach; (b) present a comprehensive ultrastructural account of selected aspects of the field; (c) point out gaps or controversial topics in our knowledge; (d) outline pertinent future research and expansion of the subject.