These are exciting days in biology; chromosome such functional attributes of chromosomes as research is no exception. Twenty years ago when replication, dosage compensation and cellular Caspersson and coworkers showed that meta­ response to DNA lesions. It is only recently that a phase chromosomes are structurally not homo­ molecular view of the meiotic cell division is geneous through their length, a new world was beginning to emerge: chapter ten refers to human in the offing. Application of various molecular meiosis and the next to molecular events in techniques in chromosome research has subse­ meiotic prophase in the baker's yeast. Another quently narrowed down the gap between the chapter is on aneuploidy in man and the Djungarian levels of microscopic and molecular understand­ hamster. The role of chromosome rearrange­ ing of chromosome organization. While complex­ ments and oncogenes in malignancy and the ities of older questions of chromosome/ parallelism between the neoplastic and phy­ chromatin organization are being understood, logenetic chromosomal alterations are discussed newer dimensions and perspectives have been in the next two chapters. Recent introduction of gained with respect to their structure and func­ potentially useful methods of chromosome isola­ tions. Even more, novel chromosome techniques tion by flow cytometry, and mapping of structural­ have become an integral component of clinical ly and functionally distinct domains on metaphase and molecular genetic methodologies.