Abstract: An improved endoscope of the variety which includes an endoscope slideably nested inside of a guiding tube, including an improvement that renders on demand either the guiding tube more flexible than the endoscope or the endoscope more flexible than the guiding tube. The improvement may be one of several embodiments, namely: (a) channels in a thermosensitive guiding tube or endoscope for circulating warm or cold fluid therein; (b) a plurality of sphere-like bodies disposed in a chamber in the guiding tube or endoscope and a vacuum system adapted to remove air or a fluid medium from the chamber; (c) a pump connected to one or more channels in a guiding tube or endoscope for providing pressurized fluid in the channels; or, (d) a flexible covering connected to and surrounding at least a part of a guiding tube delimiting a space between the covering and the guide tube, the space being in communication with a means to supply fluid of a predetermined temperature and pressure to the space.