Decades before the recent advances in molecular biology and the knowledge of the complete nucleotide sequence of several genomes, cytogenetic analysis provided the first information concerning the genome organisation. The exploration of molecular biology techniques in the cytogenetic area represents a powerful tool for advancement in the construction of physical chromosome maps of the genomes. The most important advances in cytogenetics comes from the physical anchorage of genetic linkage maps in the chromosomes through the hybridisation of DNA markers onto chromosomes. This book presents and discusses current research in the study of animal genomes under the focus of cytogenetics.