Apparatus for visualizing tissue, the apparatus comprising: - a tube sized to receive visualization apparatus disposed within the lumen of the tube, - an outer jacket disposed along the external surface of the tube, - a helical thread (735;735A;735B) disposed on an exterior surface of the outer jacket, - the helical thread (735;735A;735B) is a deformable helical profile with a hollow and inflatable lumen which can be dilated or reduced depending on the filling with a fluid, the deformable helical thread (735;735A;735B) (i) being transformable between a first configuration wherein the deformable helical thread (735;735A;735B) comprises a reduced profile and/or a reduced rigidity, and a second configuration in which the deformable helical thread (735;735A;735B) comprises an expanded profile and/or an increased rigidity, and (ii) when in its second configuration, having a sufficient structural integrity, and a sufficient surface profile, such that when the tube is disposed in a bodily passageway so that the deformable helical thread (735;735A;735B) engages the interior side wall of the bodily passageway, rotation of the tube will induce a relative movement between the tube and the side wall of the bodily passageway such that the tube is pulled gently along the interior side wall of the bodily passageway; - wherein a thread varying element is provided for dynamically varying at least one of the height of the deformable helical thread (735;735A;735B) and the rigidity of the deformable helical thread (735;735A;735B), characterized in that the tube is a corrugated or convoluted tube; and wherein the fluid for inflating the helical thread (735;735A;735B) is passed to the helical thread (735;735A;735B) through the space located between the corrugated or convoluted tube and the outer jacket. - a tube sized to receive visualization apparatus disposed within the lumen of the tube, - an outer jacket disposed along the external surface of the tube, - a helical thread (735;735A;735B) disposed on an exterior surface of the outer jacket, - the helical thread (735;735A;735B) is a deformable helical profile with a hollow and inflatable lumen which can be dilated or reduced depending on the filling with a fluid, the deformable helical thread (735;735A;735B) (i) being transformable between a first configuration wherein the deformable helical thread (735;735A;735B) comprises a reduced profile and/or a reduced rigidity, and a second configuration in which the deformable helical thread (735;735A;735B) comprises an expanded profile and/or an increased rigidity, and (ii) when in its second configuration, having a sufficient structural integrity, and a sufficient surface profile, such that when the tube is disposed in a bodily passageway so that the deformable helical thread (735;735A;735B) engages the interior side wall of the bodily passageway, rotation of the tube will induce a relative movement between the tube and the side wall of the bodily passageway such that the tube is pulled gently along the interior side wall of the bodily passageway; - wherein a thread varying element is provided for dynamically varying at least one of the height of the deformable helical thread (735;735A;735B) and the rigidity of the deformable helical thread (735;735A;735B), characterized in that