Spermatozoa (sperm) are the male sex cells that carry a man's genetic
material. They are so tiny that they can't be seen without a microscope. In a healthy man, one ejaculation usually contains between 40 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 a woman's egg (ovum) by breaking through the
membrane that surrounds the egg.
Sperm develop in a man's
testicles. They are added to semen before a man ejaculates.
ByHealthwise Staff Primary Medical ReviewerE. Gregory Thompson, MD - Internal Medicine Adam Husney, MD - Family Medicine Specialist Medical ReviewerAvery L. Seifert, MD - Urology