system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How does frozen sperm remain viable?

How does sperm survive being frozen for an amount of time?
gpt
The main issue with freezing is ice crystals forming that puncture the cell membrane and uneven freezing leaving some parts still functional, but unable to function because other parts they need to function are already frozen.

At small enough sizes (about mouse size) we can freeze things rapidly enough that the ice crystals are really small, so they won't puncture the cell, and the frozen gradient is also really small, basically the whole things freezes and thaws at the same time.

Then, it turns out, being frozen doesn't actually affect the ability of a cell to function as long as you avoid those two issues.