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 StaffPrimary Medical ReviewerE. Gregory Thompson, MD - Internal MedicineAdam Husney, MD - Family MedicineAvery L. Seifert, MD, FACS - Urology