Which storage temperature is used for frozen semen?

• A. Dry Ice at -109 degrees F
• B. Liquid Nitrogen at -252 degrees F
• C. Liquid Nitrogen at -196 degrees F
• D. Liquid Nitrogen at -320 degrees F

Answer: (D)

Preserving semen long-term requires getting it to an extremely low temperature where cellular activity nearly stops and ice damage is minimized. Liquid nitrogen holds at about −196°C, which is roughly −321°F. The option listing liquid nitrogen at about −320°F is essentially the same temperature, so it’s the best fit for storage. The other temperatures aren’t appropriate: dry ice at −109°F is not cold enough for cryogenic preservation; a temperature of −252°F is around −157°C, warmer than −196°C and thus not ideal for full halt of processes; and −196°F is about −129°C, which is not cold enough to achieve the same level of preservation as −196°C.