Several embodiments of the present invention are generally directed to medical visualization systems that comprise combinations of disposable and reusable components, such as catheters, functional handles, hubs, optical devices, etc. Other embodiments of the present invention are generally directed to features and aspects of an in-vivo visualization system that comprises an endoscope having a working channel through which a catheter having viewing capabilities is routed. the catheter may obtain viewing capabilities by being constructed as a vision catheter or by having a fiberscope or other viewing device selectively routed through one of its channels. The catheter is preferably of the steerable type so that the distal end of the catheter may be steered from its proximal end as it is advanced with the body. A suitable use for the in-vivo visualization system includes but is not limited to diagnosis and/or treatment of the duodenum, and particularly the biliary tree.