An endoscope has a sterilizable, elongated, optical capsule section and a separable, disposable, sterile channel section. The capsule has a window at a distal end in front of an image sensor. Image transmitting electronic cables, connected to the image sensor, extend proximally from the capsule. Light transmitting fibers extend from the window proximally for transmitting light to a site under investigation from a remote light source. The cables and the fibers are housed in a common conduit connected to the proximal end of the capsule. The separable channel section has a distal end removably attached to the capsule and has plurality of longitudinal channels for transmitting fluids or for receiving an operative instrument. A flexible tube is connected to the proximal end of each channel for supplying fluid or for manipulating the operative instrument from a remote location. The separable channel section is disposable after use. The capsule is sterilizable for reuse with another sterile separable channel section on the next patient. The separable channel section can be used with a conventional endoscope. The conventional endoscope can be covered with a sterile sheath to minimize resterilization thereof. An umbilicated balloon catheter or a telescopic catheter can be used to position the endoscope in a passageway. Circumferentially spaced fluid vents can supply jets of gas or liquid selectively to position the endoscope. Alternatively, a magnet can be used for manipulating a capsule with a ferrous housing along a passageway by use of a strong magnet located exteriorly thereof.