In recent years excellent progress has been the study of these disorders in the future. made in the development of improved Recently freeze fracture techniques have cytochemical and ultrastructural tech- also been employed in the study of rmal niques for electron microscopy in hematol- and leukemic lymphocytes and much new ogy and in particular in leukemia and information concerning leukemic cell lymphoma. Subtypes of these disorders, membranes may be obtained from the use which are essentially classified according to of this technique in the future. cell phetype and the degree of matura- The purpose of this book is to demon- tion, can be well defined today using a strate the utility of these techniques in combination of immulogical methods, defining leukemic cell types and to illus- light microscopy, cytochemistry, and elec- trate the potential of some of the newer tron microscopy. Ultrastructural cyto- ultrastructural methods, including trans- chemistry is w utilized routinely in mission and scanning immu electron leukemia in most major centers today and microscopy, SEM cytochemistry, and can also be performed using scanning elec- freeze fracture techniques, in the study of tron microscopy (SEM), as described in leukemia. Advances in cytochemical tech- this book. Immu electron microscopy niques and their use in the definition of used with or without simultaneous ultra- nlymphoid cells and in the classification structural cytochemistry can also be em- of lymphoid subtypes are clearly demon- ployed in the accurate classification of strated in this book.