A controlled-rate freezer, often abbreviated to CRF, cools samples gradually at a precisely programmed rate, historically the standard approach for freezing embryos and other reproductive tissue. Vitrification, by contrast, cools samples extremely rapidly, effectively skipping the temperature range where damaging ice crystals form, and has become the more widely used method for embryos and oocytes in most IVF laboratories today. Both methods remain in active use depending on sample type and clinical protocol. Cryolab has deep roots in this specific technology: Paul Hague was International Sales Manager at Planer, a leading UK manufacturer of controlled-rate freezers, before founding Cryolab, and personally demonstrated CRF technology to Professor Robert Edwards, the Nobel Prize-winning pioneer of IVF.