Cryo tubes – also referred to as cryogenic storage tubes or cryovials – are small, sealable containers used to store biological samples at cryogenic temperatures, typically in liquid nitrogen at -195.8 degrees C or in the vapour phase above it. In an IVF laboratory, cryo tubes are used to store sperm samples, tissue biopsies, and other cellular material that requires long-term cryopreservation.
What distinguishes a cryo tube from other cryogenic storage containers?
A cryo tube is distinguished from a straw or visotube primarily by its format and intended use. Straws – typically 0.3ml or 0.5ml in volume – are the standard container for embryo and sperm cryopreservation in clinical IVF, where precise volume control and the ability to load into a warming device are required. Cryo tubes offer larger volumes, typically 1.8ml or 2ml, and are more commonly used for sperm banking, research samples, and cell lines where sample volume, ease of labelling, and retrieval are the primary considerations.
What material should cryo tubes be made from?
Cryogenic storage tubes must be manufactured from polypropylene or similar materials that maintain structural integrity at -195.8 degrees C without becoming brittle or cracking. The seal must be airtight to prevent liquid nitrogen ingress into the sample, which can cause the tube to explode violently on warming. Externally threaded cryo tubes are generally preferred over internally threaded designs for cryogenic use, as the internal thread presents a contamination risk if liquid nitrogen enters the thread channel.
How are cryo tubes organised within a storage vessel?
Cryo tubes are typically organised within cryogenic storage boxes, which sit inside the canisters of a liquid nitrogen storage vessel. Box capacity varies, but standard formats hold 81 or 100 tubes in a grid arrangement. Clear labelling of both the tube and the storage box is essential for traceability and for meeting HFEA documentation requirements in licensed settings.
Cryo tube selection should always be driven by the sample type, the storage format in use, and the downstream processing requirements – not by unit cost alone. A tube that fails at cryogenic temperature is not just a lost sample; it is a traceability event that must be documented and reported.
Cryolab supplies cryogenic storage consumables for IVF and research applications, including cryo tubes compatible with standard cryogenic storage vessels. Browse the full range at cryolab.co.uk/ivf-consumables/.
