Part 4 Week by Week:
Facts about sperm health and lifespan
They stick around longer than you'd think. We may also share information with our advertising partners. Sperm cells - which are made in the testicles - need lots of high-octane fuel to whip their tails. A man's body keeps the ideal testicle temperature with radiator-like veins that pull heat away and muscles in the scrotum that raise and lower the testicles to bring them closer to the body's warmth - or farther away. In the hot tub, sperm cells do not live for very long at all.