A Caltech biologist who was the first to explain how genes control the development of organs during the early growth of an embryo will share the 1995 Nobel Prize in physiology and medicine with researchers from Princeton University and Germany who followed up on his pioneering discovery.

Edward B. Lewis, 77, of Caltech, Eric F. Wieschaus, 48, of Princeton and Christiane Nuesslein-Volhard, 52, of the Max Planck Institute for Developmental Biology in Tubingen, Germany, received the award for explaining how an essentially shapeless fertilized egg develops into an organism with a front and back, head and feet and right and left sides.

Although all three worked with fruit flies, they "have achieved a breakthrough that will help explain congenital malformations in man" as well, according to the Nobel citation released Monday in Stockholm. "It is likely that mutations {in the genes they discovered} are responsible for some of the early, spontaneous abortions in {humans} and for some of the about 40% of the congenital malformations that develop due to unknown reasons."