The overall objects of this research is to identify and characterize the pulmonogenic areas of the chick embryo until the lung and its vasculature are fully formed. Lung bud morphology, histology and development potentialities in normal and abnormal environment will be defined, as well as relationships to other derivates of the foregut and splanchnic mesoderm, including the heart. Research goals for the coming year are to continue to identify the fate of the embryonic material that forms the sixth aortic arches, and to study the effects of arch ablation on lung development. In addition, studies are underway to investigate the development of the conotruncus, both after alteration of blood flow patterns in the embryonic heart and its role in TGA. Some of these studies will be in collaboration with Dr. Dennis Morse of Toledo, Ohio, who will do Scanning Electron Microscopy on embryonic specimens. Additional acrylic injections will be prepared and the atlas referred to above will be completed. Studies are also underway to investigate embryonic cardiac function by detailed study of cine films of the embryonic heart. These studies will be in collaboration with Dr. Roger Ruckman, also of the Department of Pediatrics at the University of Nebraska Medical Center.