[The homeo box--a genetic key to fetal development].

A fundamental question in medicine and biology is how does a fertilized oocyte develop into an adult organism. By combining classical genetics, experimental embryology and gene technology it is now possible to analyze how the complicated process of embryogenesis is regulated by genes. One important genetic element in this regard is the homeobox, which was initially discovered in the genes controlling the early development of the fruit fly Drosophila melanogaster. The homeobox is also present in the genomes of vertebrates, and this discovery has shed new light upon the mechanisms which establish the formation of cell patterns in complex species, such as humans.