A device for preserving a predetermined dose of liquid-based substance, notably animal semen or a preservation medium containing embryos or tissue samples, comprises a tube (11) made of a weldable plastics material. The tube allows a service state in which a receiving portion (21) intended to contain the said predetermined dose has a circular cross-section whereas a sealing portion (22) comprises a welded pinch (19) and a transition zone (23). Over at least part of the sealing portion a differentiating edge region (28) gives the external surface of the tube a visual appearance different from the visual appearance of the external surface of the tube outside of the differentiating edge region. A range comprises such a device and a similar device but without the differentiating edge region.
