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: April 9, 2025
Author: Ignite Healthwise, LLC Staff
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Current as of: April 9, 2025