This invention is related to devices and systems for creating sutureless anastomoses. In particular, this invention is related to devices for deploying and securing the ends of bypass grafts designed to provide a fluid flow passage between at least two vessels or tubular structures. A variety of compressible, expandable fittings, loading and delivery sheaths, tools, and other devices for creating end-end and end-side anastomoses, as well as methods for their use, are disclosed. In addition, robotic, remotely operable systems and devices for creating sutureless anastomoses in minimally invasive applications are disclosed. The systems of this invention do not require stopping or re-routing blood flow to perform an anastomosis between a bypass graft and a host vessel. Accordingly, this invention describes sutureless anastomosis systems that do not require cardiopulmonary bypass support when treating coronary artery disease.