Summary
Highlights
Sperm are tiny cells produced by male reproductive organs, primarily composed of water, plasma, and mucus. They contain 5-25 calories and small amounts of essential nutrients like calcium. Millions are produced daily, though only one is needed to fertilize an egg.
Sperm are only visible under a microscope due to their minuscule size. Scientists identify three main parts: the head, midsection, and tail. The head contains chromatin (DNA material with 23 chromosomes), and an acrosome cap with enzymes to penetrate an egg. The midsection houses energy-producing mitochondria for movement. The tail, a complex structure with over a thousand proteins, was previously thought to sway like a snake but 3D microscopy reveals it spins like a drill.
Sperm morphology refers to the shape of the sperm, including head size, DNA content, midpiece appearance, and tail structure. Sperm can be malformed with abnormal head sizes, extra heads, or absent heads/tails. Other defects include bent, coiled, or stump tails, or tails attached incorrectly. Teratozoospermia, an increase in abnormally shaped sperm (over 96%), can directly impact fertility due to the sperm's need for a specific shape to reach and penetrate the egg. While most men with abnormal sperm morphology can still father children, it may take longer or require fertility assistance.