For life-threatening medical emergencies, call 911 without delay. For a mental health crisis, call or text 988 for free and confidential crisis support.
Spermatozoa (sperm) are the male sex cells that carry genetic material. They are so tiny that they can't be seen without a microscope. One ejaculation usually contains between 20 million and 600 million sperm.
Sperm have an oval head, a short middle, and a long tail. They move by whipping their tails. A sperm fertilizes an egg (ovum) by breaking through the membrane that surrounds the egg.
Sperm develop in the testicles. They are added to semen before ejaculation.
Current as of:
February 27, 2023
Author: Healthwise Staff Clinical Review Board All Healthwise education is reviewed by a team that includes physicians, nurses, advanced practitioners, registered dieticians, and other healthcare professionals.
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