The genetic code information programs the embryogenesis. Human genetic research generates knowledge with the potential to improve individual and community health. Research can also reveal information about an individual's susceptibility to disease and hence about the individual's future health. Mapping also provides clues about which chromosome contains the gene and precisely where the gene lies on that chromosome. Furthermore, new approaches for the detection of DNA polymorphism are constantly emerging. This book covers these hot topics in considerable detail, and is set apart by its combination of genetic and physical mapping. The book explains current strategies for mapping genomes of organisms and explores applications of gene mapping to human. In this book the three phases of prenatal development the pre-embryonic, the embryonic and the fetal are elaborated.