Cryopreservation

Sperms, eggs and embryos are cryopreserved (frozen) from body temperature down to -196°C (-320° F) and stored in containers of liquid nitrogen called dewars. The gametes / embryos are kept within special labelled plastic vials, or straws, that are sealed prior to freezing.
Freezing is generally done for a period of one year and then renewed according to the need of the patient.