A diagnostic, surgical and/or therapeutic device for being introduced into the human or animal body or for in-vitro examination of human or animal blood samples or other body cells; in particular an endoscope or single-use endoscope comprising at least one illumination light guide and/or image guide for transmitting electromagnetic radiation, wherein said illumination light guide or image guide has a proximal end face for injection or emission of electromagnetic radiation and a distal end face for emission or injection of electromagnetic radiation; wherein said proximal and/or distal end faces (43, 53) consist of elements made of plastics material, which are transparent at least partially or in sections thereof, or have a transparent plastics material overmoulded thereon; wherein said transparent plastics material is biocompatible and/or non-cytotoxic to human or animal cell cultures over exposure durations of less than one day, and is selected from the group consisting of cyclic olefin copolymers, polycarbonates, polyethylene terephthalates, perfluoroalkoxy polymers, polyvinylidene fluorides, polymethyl methacrylates, polymethyl methacrylimides, acrylic styrene acrylonitrile copolymers, or room temperature crosslinking silicone, hot crosslinking liquid silicones, epoxy casting resins or adhesives, thermally or UV crosslinking acrylate casting resins, polyurethane casting resins, polyester casting resins, or mixtures and/or combinations thereof; and wherein the illumination light guide or image guide is made up of a fibre bundle consisting of glass optical fibres, quartz optical fibres, or plastic optical fibres, and/or comprises individual fibres made of these materials, which are enclosed at least partially or in sections thereof by a jacket, and wherein the jacket is made of a further plastics material, and is provided in the form of an extruded cable; characterised in that the jacket is made from a thermoplastic elastomer. in particular an endoscope or single-use endoscope comprising at least one illumination light guide and/or image guide for transmitting electromagnetic radiation, wherein said illumination light guide or image guide has a proximal end face for injection or emission of electromagnetic radiation and a distal end face for emission or injection of electromagnetic radiation; wherein said proximal and/or distal end faces (43, 53) consist of elements made of plastics material, which are transparent at least partially or in sections thereof, or have a transparent plastics material overmoulded thereon; wherein said transparent plastics material is biocompatible and/or non-cytotoxic to human or animal cell cultures over exposure durations of less than one day, and is selected from the group consisting of cyclic olefin copolymers, polycarbonates, polyethylene terephthalates, perfluoroalkoxy polymers, polyvinylidene fluorides, polymethyl methacrylates, polymethyl methacrylimides, acrylic styrene acrylonitrile copolymers, or room temperature crosslinking silicone, hot crosslinking liquid silicones, epoxy casting resins or adhesives, thermally or UV crosslinking acrylate casting resins, polyurethane casting resins, polyester casting resins, or mixtures and/or combinations thereof; and wherein the illumination light guide or image guide is made up of a fibre bundle consisting of glass optical fibres, quartz optical fibres, or plastic optical fibres, and/or comprises individual fibres made of these materials, which are enclosed at least partially or in sections thereof by a jacket, and wherein the jacket is made of a further plastics material, and is provided in the form of an extruded cable; characterised in that the jacket is made from a thermoplastic elastomer.