A method of cryopreserving sperm cells which may include cooling the quantity of sperm cells to a holding temperature, maintaining the sperm cells substantially at the holding temperature for a period, and supercooling the sperm cells by cooling the sperm cells at a first cooling rate to a temperature that approaches a critical temperature zone at which ice crystal formation and changes in osmotic pressure damage sperm cells and then cooling the sperm at a second cooling rate faster than said first cooling rate through said critical temperature zone.